Process to prevent polymer scale adhesion using condensation product of an aromatic amine and a quinone

ABSTRACT

A polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising an alkaline solution containing a condensation product of (A) an aromatic amine compound and (B) a quinone compound. This process is used for forming a coating on the inner wall, etc. of a polymerization vessel. Such a vessel is effective in preventing polymer scale deposition and useful in producing a polymer that shows very few fish eyes and good whiteness when formed into sheets or the like.

This is a Division of application Ser. No. 07/964,267 filed on Oct. 21, 1992, now U.S. Pat. No. 5,424,003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polymer scale preventive agent useful in polymerization of a monomer having an ethylenically unsaturated double bond, a polymerization vessel effective in preventing polymer scale deposition, and a process of producing a polymer using said vessel.

2. Description of the Prior Art

As a method of polymerizing a monomer having an ethylenically unsaturated double bond, are known suspension polymerization, emulsion polymerization, solution polymerization, gas phase polymerization and bulk polymerization. In any type of the polymerizations, polymer scale is liable to be deposited on the areas with which the monomer come into contact during polymerization, such as inner walls, stirring equipment and so on of a polymerization vessel.

The deposition of the polymer scale on the inner wall results in disadvantages that the yield of the polymer and cooling capacity of the polymerization vessel are lowered; that the polymer scale may peel and mix into a polymeric product, thereby impairing the quality of thereof; and that removal of such polymer scale is laborious and hence time-consuming. Further, since the polymer scale contains unreacted monomers and operators may be exposed thereto, which may cause physical disorders in the operators.

Heretofore, as a method for preventing polymer scale deposition on the inner wall and so forth, methods by which a polymer scale preventive agent comprising an amine compound, quinone compound, aldehyde compound or the like is coated on the inner wall, etc. of a polymerization vessel or methods by which such compounds are added to an aqueous medium for polymerization (Japanese Patent Publication (KOKOKU) No. 45-30343 (1960)).

These methods can prevent the deposition of polymer scale if polymerization run is repeated within about 5 or 6 times; however, the number of repetition of polymerization run exceeds 5 or 6, the scale preventive effect is weakened. That is, the scale preventive effect is poor in durability. Particularly, the scale preventive effect is adversely affected where a water-soluble catalyst is used and unsatisfactory industrially.

It is proposed in Japanese Pre-examination Patent Publication (KOKAI) No. 53-13689(1978) to form a coating of a condensation product of an aromatic amine compound on the areas with which monomers comes into contact, such as the inner wall of a polymerization vessel. The formation of the coating of such a condensation product enables repetition of about 100 to 200 polymerization runs without deposition of polymer scale on the areas in the liquid phase, i.e., under the liquid surface inside the polymerization vessel.

However, polymer scale deposition is liable to occur in the vicinity of the interface between the gas phase and the liquid phase which is located at the upper section of a polymerization vessel. Once polymer scale is deposited in the vicinity of the interface between the gas phase and the liquid phase, the deposited scale will grow gradually as polymerization runs are repeated, and at last it is peeled from the inner wall, etc. and incorporated into the polymeric product. If the polymeric product containing the polymer scale is processed into formed products such as sheets or the like, the polymer scale causes increase in fish eyes in the formed products, lowering seriously the quality thereof.

Polymeric products obtained by polymerization are required to have a high whiteness. That is, when a polymeric product is formed into a sheet or the like without any addition of a coloring agent, the resulting formed product is more or less colored. Such coloration is called initial coloration, which is desired to be as low as possible. However, the coating comprising said condensation product of an aromatic amine compound disclosed in the Japanese Pre-examination Publication may be peeled or dissolved into a polymeric product, thereby lowering the whiteness or increasing the initial coloration thereof.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide a polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond that can prevent effectively the deposition of polymer scale not only in the areas in the liquid phase but also in the vicinity of the interface between the gas and liquid phases, and can produce polymeric products with a very small number of fish eyes and low initial coloration after processed into formed products such as sheets or the like, a polymerization vessel using the same, and a process of producing a polymer using the vessel.

Thus, the present invention provides, as a means of achieving the above object, a polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising an alkaline solution containing a condensation product of (A) an aromatic amine compound and (B) a quinone compound.

The present invention also provides a polymerization vessel for use in polymerization of a monomer having an ethylenically unsaturated double bond, having on its inner wall surfaces a polymer scale preventive coating, wherein said coating has been formed by applying an alkaline solution containing a condensation product of (A) an aromatic amine compound and (B) a quinone compound, followed by drying.

Further, the present invention provides a process of producing a polymer of an ethylenically unsaturated double bond, which comprises polymerizing the monomer in a polymerization vessel having a polymer scale preventive coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution containing a condensation product of (A) an aromatic amine compound and (B) a quinone compound, followed by drying.

According to the present invention, deposition of polymer scale can be effectively prevented not only on the areas in the liquid phase but also in the vicinity of the interface between the gas and liquid phases in a polymerization vessel. Therefore, the present invention makes it unnecessary to conduct the operation of removing the polymer scale after every polymerization run, and the productivity is thereby improved.

Further, when the polymeric product obtained by the application of the present invention is processed into formed products such as sheets, the resulting formed products have very few fish eyes.

Furthermore, the formed products obtained as above is low in initial coloration. That is, the formed products exhibit a luminosity index L in the Hunter's color difference equation described in JIS Z 8730(1980) of 70 or more in the case of vinyl chloride polymers and 80 or more in the case of SBR.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS (A) Aromatic Amine Compound

The aromatic amine compounds (A) are classified into (A-1) aromatic amine compounds having at least one group selected from the group consisting of hydroxyl group, carboxyl group and sulfo group (--SO₃ H) and (A-2) aromatic amine compounds free of hydroxyl group, carboxyl group and sulfo group.

(A-1) Aromatic amine compounds having at least one group selected from the group consisting of hydroxyl group, carboxyl group and sulfo group (--SO₃ H)

The aromatic amine compounds (A-1) include, for example, the compounds represented by the general formulas (1) to (3). ##STR1## wherein m is an integer of 1 to 5, R¹ stands for at least one group selected from the group consisting of --OH, --COOH and --SO₃ H and, where there exist two or more R¹ 's, the R¹ 's may be the same or different, and R² stands for at least one group selected from the group consisting of --H, --NH₂, --Cl, --NO₂, --COCH₃, --OCH₃, --N(CH₃)₂ and alkyl groups having 1 to 3 carbon atoms and, where there exist two or more R² 's, the R² 's may be the same or different.

Specifically, the compounds of the general formula (1) include, for example, o-, m- or p-aminophenol, 2-amino-4-chlorophenol, 5-nitro-2-aminophenol, 2-nitro-4-aminophenol, 4-nitro-2-aminophenol, o-, m- or p-aminobenzoic acid, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5- or 4,6-diaminobenzoic acid, 3- or 4-aminophthalic acid, 2-,4- or 5-aminoisophthalic acid, 4,6-diaminoisophthalic acid, 2,5- or 2,6-diaminotelephthalic acid, 3-,4- or 5-aminosalicylic acid, 4-hydroxyanthranilic acid, o-, m- or p-aminobenzenesulfonic acid, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-diaminobenzenesulfonic acid, 2-amino-1-phenol-4-sulfonic acid, 6-amino-4-nitro-1-phenol-2-sulfonic acid and 6-amino-4-chloro-1-phenol-2-sulfonic acid. ##STR2## wherein m is as defined above, R¹ is as defined above and, where two or more R¹ 's are present, they may be the same or different, R² is as defined above and, where two or more R² 's are present, they may be the same or different, and n is an integer of 0 to 5.

Specifically, the compounds of the general formula (2) include, for example, 4-hydroxydiphenylamine, 4-amino-4'-hydroxydiphenylamine, 4-carboxydiphenylamine, 4-amino-4'-carboxydiphenylamine, 4-sulfodiphenylamine and 4-amino-4'-sulfodiphenylamine. ##STR3## wherein p is an integer of 0 to 4, q is an integer of 0 to 3, provided that p and q are not 0 at the same time, R² is as defined above and, where two or more R² 's are present, they may be the same or different, and R³ is at least one group selected from the group consisting of --OH, --COOH, --CH₂ COOH, --CH₂ CH₂ COOH and --SO₃ H and, where two or more R³ 's are present, they may be the same or different.

Specifically, the compounds of the general formula (3) include, for example, 4-amino-1-naphthol, 1-amino-5-naphthol, 1,2-naphtyldiamine-7-carboxylic acid, 1,5-naphthalenediamine-2-carboxylic acid, 1,5-naphthalenediamine-4-carboxylic acid, 1,6-naphthalenediamine-4-carboxylic acid, 1,8-naphthalenediamine-4-carboxylic acid, 1,2-naphthalenediamine-3-sulfonic acid, 1,2-naphthalenediamine-4-sulfonic acid, 1,2-naphthalenediamine-5-sulfonic acid, 1,2-naphthalenediamine-6-sulfonic acid, 1,2-naphthalenediamine-7-sulfonic acid, 1,3-naphthalenediamine-5-sulfonic acid, 1,3-naphthalenediamine-6-sulfonic acid, 1,4-naphthalenediamine-2-sulfonic acid, 1,4-naphthalenediamine-7-sulfonic acid, 1,5-naphthalenediamine-2-sulfonic acid, 1,5-naphthalenediamine-4-sulfonic acid, 1,5-naphthalenediamine-7-sulfonic acid, 1,6-naphthalenediamine-2-sulfonic acid, 1,6-naphthalenediamine-4-sulfonic acid, 1,6-naphthalenediamine-7-sulfonic acid, 1,8-naphthalenediamine-4-sulfonic acid, 1,8-naphthalenediamine-3,6-disulfonic acid, 1,8-naphthalenediamine-4,5-disulfonic acid, α-amino-β-naphthalenepropionic acid, α-amino-β-naphthalenecaroboxylic acid, 2-naphthylamine-1-sulfonic acid, 8-naphthylamine-1-sulfonic acid, 5-naphthylamine-1-sulfonic acid, 1-amino-2-naphthol-4-sulfonic acid, 2-amino-8 -naphthol-6-sulfonic acid (gamma acid), 2-amino-5-naphthol-7-sulfonic acid (J acid), 1-amino-8-naphthol-3,6-disulfonic acid (H acid) and the like.

Among the compounds (A-1), preferred are o-, m- or p-aminophenol, 2,4- or 2,5-diaminobbenzenesufonic acid, 2,3-, 2,4-, 2,5-, 3,4- or 3,5-diaminobenzoic acid, 4,6 -diaminoisophthalic acid, 2,5- or 2,6-diaminotelephthalic acid, 2,5- or 2,6-diaminotelephthalic acid, 1,2-naphthalenediamine-7-sulfonic acid, 1,5- or 1,6-naphthalenediamine-4-sulfonic acid, 1,5- or 1,6-naphthalenediamine-4-carboxylic acid.

(A-2) Aromatic amine compounds free of hydroxyl group, carboxyl group and sulfo group

The compounds (A-2) include, for example, the compounds represented by the general formulas (4) to (6). ##STR4## wherein R² may be the same or different and are each as defined above.

Specifically, the compounds of the general formula (4) include, for example, aniline, o-, m- or p-phenylenediamine, o-, m- or p-chloroaniline, o-, m- or p-nitroaniline, o-, m- or p-methylaniline, N,N-dimethyl-p-phenylenediamine, 4-chloro-o-phenylenediamine, 4-methoxy-o-phenylenediamine, 2,3-diaminotoluene and the like. ##STR5## wherein R² may be the same or different and are each as defined above.

Specifically, the compounds of the general formula (5) include, for example, 4-aminodiphenylamine, 2-aminodiphenylamine, 4,4'-diaminodiphenylamine and 4-amino-3'-methoxydiphenylamine. ##STR6## wherein R² may be the same or different and are each as defined above.

Specifically, the compounds of the general formula (6) include, for example, α-naphthylamine, β-naphthylamine, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene and the like.

Among the compounds (A-2), preferred are o-, m- or p-phenylenediamine, 2- or 4-aminodiphenylamine, 4,4'-diaminodiphenylamine, and 1,5- or 1,8-diaminonaphthalene.

The aromatic amine compounds (A) may be used singly or in combination of two or more.

As the aromatic amine compound (A), at least one compound selected from the group consisting of the compounds (A-1) and the compounds (A-2) needs to be used. Preferably, at least one compound (A-1) is used, and more preferably a compound (A-1) and a compound (A-2) are used in combination.

(B) Quinone Compound

The quinone compounds include, for example, the compounds represented by the general formulas (7), (8), (9) and (10): ##STR7## wherein R⁴ stands for --H, --NH₂, --Cl, --Br, --OH, --NO₂, --COCH₃, --OCH₃, --N(CH₃)₂ or an alkyl group having 1 to 3 carbon atoms, and R⁵ stands for --H, --NH₂, --OH, --CH₃, --COOH or --SO₃ H. ##STR8## wherein R⁴ and R⁵ are as defined above.

Specifically, examples of the compounds of the general formula (7) or (8) include o-, m- or p-benzoquinone, hydroxy-p-benzoquinone, chloro-p-benzoquinone, bromo-p-benzoquinone, duroquinone, chloranil. ##STR9## wherein R⁴ and R⁵ are as defined above, and R⁶ stands for --H, --OH, --CH₃, --Cl, --Br, --COCH₃, --OCH₃, --COOH or --SO₃ H; and ##STR10## wherein R⁴, R⁵ and R⁶ are as defined above.

Specifically, examples of the compounds of the general formula (9) or (10) include 6-methyl-1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, lawsone, juglone, plumbagin, α-naphthoquinone, and β-naphthoquinone.

Among the quinone compounds above, preferred are o- or p-benzoquinone, α-naphthoquinone, β-naphthoquinone and lawsone.

The quinone compounds may be used singly or in combination or two or more.

Condensation Reaction

The condensation product of the aromatic amine compound (A) and the quinone (B), which is the effective component of the present polymer scale preventive agent, can be prepared by reacting the components (A) and (B) optionally in the presence of a catalyst at a temperature of room temperature to about 200° C. in a suitable medium for about 0.5 to 100 hours, preferably at a temperature of from room temperature to 150° C. for 3 to 30 hours.

In the condensation reaction above, the quinone compound acts as a catalyst; therefore, normally it is not necessary to add another condensation catalyst. Nevertheless, a condensation-catalyst may be added to the reaction system on the case-by-case basis. Condensation catalysts include, for example, azo compounds such as α,α'-azobisisobutyronitrile and α,α'-azobis-2,4-dimethylvaleronitrile, elemental or molecular halogens such as iodine, bromine and fluorine, inorganic peroxides such as hydrogen peroxide, sodium peroxide, potassium persulfate, and ammonium persulfate, organic peroxides such as peracetic acid, benzoyl peroxide, cumene hydroperoxide, perbenzoic acid and p-menthane hydroperoxide, oxyacids or salts thereof such as iodic acid, periodic acid, potassium periodate and sodium perchlorate, metallic salts such as ferrous oxide, ferric oxide, copper sulfate, copper (I) oxide, and ferric chloride, and aromatic nitro compounds such as nitrobenzene, o-, m- or p-hydroxynitrobenzene, o-, m- or p-nitroanisole, o-, m- or p-chlorobenzene, o-, m- or p-nitrobenzenesulfonic acid, etc.

The solvents for the condensation reaction include organic solvents such as, e.g., alcohols, ketones and esters, among which organic solvents compatible with water are preferred. The organic solvents compatible with water include, for example, alcohols such as methanol, ethanol and propanol, ketones such as acetone, methyl ethyl ketone, and the like, and esters such as methyl acetate and ethyl acetate, out of which alcohols are particularly preferred. Mixed solvents of water and an organic solvent compatible with water can be also used.

The reaction medium for the condensation reaction normally has a pH of 1 to 13. A pH adjuster is not particularly limited.

Although the amounts of the aromatic amine compound (A) and the quinone compound (B) subjected to the condensation reaction depends on the kinds of the aromatic amine compound (A), the quinone compound (B) and solvent, reaction temperature, reaction time, etc., normally the quinone compound (B) is used in an amount of about 0.01 to about 10 parts by weight, preferably 0.1 to 5 parts by weight, per part by weight of the aromatic amine compound (A). If the amount of the component (B) is too small or too large relative to that of the component (A), the resulting condensation product is poor in polymer scale preventing effect.

In a preferred embodiment of the present invention, a compound (A-1) is used as the component (A), and more preferably a compound (A-1) and a compound (A-2) are used in combination as the component (A). In the preferred embodiment, more improved polymer scale preventing effects are obtained. Presumably, this is because the combined use of the compound (A-1) and the compound (A-2) increases the adhesion of the condensation product to the inner wall surfaces, etc. of a polymerization vessel when an alkaline solution containing the condensation product is applied thereto as described later. Where the two aromatic amine compounds (A-1) and (A-2) are used in combination, the compound (A-2) is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per part by weight of the compound (A-1).

(C) Reaction Stopper

If the condensation product of the components (A) and (B) has too high a degree of condensation, when it is dissolved in a solvent to prepare a polymer scale preventive agent described later, it may form sediment and the polymer scale preventive agent obtained is not uniform, thereby lowering the scale preventing effect. Therefore, it is preferable to add (C) a reaction stopper to the reaction mixture at an suitable time during the condensation reaction of the components (A) and (B), so that further progress of the condensation is inhibited and the degree of condensation is controlled. Further, the addition of the reaction stopper (C) makes it possible to store the condensation product of the components (A) and (B) for a long time.

As the reaction stopper (C), for instance, inorganic reducing agents (C-1), aromatic hydroxyl compounds (C-2) and aromatic hydroxyl compound-based condensation products (C-3) can be used, as described below.

(C-1) Inorganic reducing agent

The inorganic reducing agent includes, for example, hydrogen, hydrogen iodide, hydrogen bromide, hydrogen sulfide, hydrides such as lithium aluminum hydride, sodium borohydride, calcium borohydride, zinc borohydride, tetraalkylammonium borohydride, trichlorosilane, triethylsilane, and the like, lower oxides or lower oxyacids such as carbon monoxide, sulfur dioxide, sodium thiosulfate, sodium thiosulfite, sodium sulfite, potassium sulfite, sodium bisulfite, and sodium hydrosulfite, sulfur compounds such as Rongalit, sodium sulfide, sodium polysulfide, and ammonium sulfide, alkali metals such as sodium and lithium, metals that are electrically highly positive such as magnesium, calcium, aluminum and zinc and their amalgams, salts of metals in a lower valence state such as iron(II) sulfate, tin(II) chloride, titanium(III) trichloride, and the like, phosphorus compounds such as phosphorus trichloride, phosphorus triiodide, trimethylphosphine, triphenylphosphine, trimethylphosphite, and hexamethylphosphorus triamide, hydrazine, diborane, and substituted diboranes such as ethane-1,2-diaminoborane, dimethylamine-borane, and pyridine-borane. Among these compounds, preferred are hydrogen iodide, hydrogen bromide, sodium borohydride, sulfur dioxide, sodium thiosulfate, sodium thiosulfite, sodium sulfite, potassium sulfite, sodium bisulfite and Rongalit.

(C-2) Aromatic hydroxyl compound

The aromatic hydroxyl compound (C-2) includes, for example, the compounds having the general formulas (11) and (12): ##STR11## wherein R⁷ stands for --H, --Cl, --OH, --COCH₃, --OCH₃, --COOH, --SO₃ H or an alkyl group having 1 to 3 carbon atoms, and R⁷ stands for --H, --Cl, --OH, --OCH₃, --OC₂ H₅ or --COOH.

Specifically, the compounds of the general formula (4) include, for example, phenols such as phenol, hydroquinone, resorcinol, catechol, hydroxyhydroquinone, pyrogallol, o-, m- or p-chlorophenol, o-, m- or p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,5-, 2,6- or 3,5-dihydroxytoluene and the like. Among the compounds, preferred are hydroquinone, resorcinol, catechol, hydroxyhydroquinone, o-, m- or p-hydroxybenzoic acid and pyrogallol. ##STR12## wherein the two R⁷ may be the same or different and are each as defined above, and R⁸ is as defined above.

Specifically, the compounds of the general formula (12) include, for example, naphthols and their derivatives such as α-naphthol, β-naphthol, 1,3-, 1,4-, 1,5-, 2,3-, 2,6- or 2,7-dihydroxynaphthalene, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid and the like. Among these, preferred are α-naphthol, β-naphthol, and 1,3- or 2,7-dihydroxynaphthalene.

The aromatic hydroxyl compounds may be used singly or in combination of two or more.

(C-3) Aromatic hydroxyl compound-based condensate

The aromatic hydroxyl compound-based condensate is a condensation product essentially comprising an aromatic hydroxyl compound described as the compound (C-2) above as a condensation reactant, and includes, for example, condensation products of an aromatic hydroxyl compound only, condensation products of an aromatic hydroxyl compound with other compounds such as, for example, acetone, aldehydes and aromatic amine compounds, natural aromatic hydroxyl-containing organic compounds, and natural flavonoid hydroxyl-containing organic compounds.

(C-3-1) Condensates of aromatic hydroxyl compound only

Any of the aromatic hydroxyl compounds exemplified above as compound (C-2) can form condensates through condensation reaction. Typical examples include the condensates of pyrogallol, resorcinol, catechol, 2,7-dihydroxynaphthalene, or 2-hydroxynaphthoquinone.

The condensate can be obtained by reacting an aromatic hydroxyl compound in the presence of a catalyst such as a peroxide, azo compound, nitro compound, halogen compound, quinone or metallic salt at a temperature of about room temperature to 100° C. in water, an organic solvent such as alcohols, ketones, and esters, or a mixed solvent of water and an organic solvent mentioned above. Specifically, the catalyst used includes, for example, peroxides such as periodic acid, potassium periodate and hydrogen peroxide, azo compounds such as α,α'-azobisisobutyronitrile, metallic salts such as ferric chloride, aromatic nitro compounds such as nitrobenzene, and aromatic quinone compounds such as p-benzoquinone.

(C-3-2) Aromatic hydroxyl compound-acetone condensate

All of the condensation products of acetone with any of the aromatic hydroxyl compounds described as (C-2) above, can be used. Typical examples of the condensates include pyrogallol-acetone condensates, resorcinol-acetone condensates, 2,7-dihydroxynaphthalene-acetone condensates, 1,5-dihydroxynaphthalene-acetone condensates, 2,6-dihydroxynaphthalene-acetone condensates, 2,3-dihydroxynaphthalene-acetone condensates, 2-hydroxynaphthoquinone-acetone condensates, alizarin-acetone condensates and the like.

The condensates above can be obtained by dissolving an aromatic hydroxyl compound in acetone, and reacting them in the presence of a catalyst at a temperature of about room temperature to 100° C. As the catalyst, phosphorus oxychloride is used, for instance.

(C-3-3) Aromatic hydroxyl compound-aldehyde condensate

The aldehyde used as one of the reactants includes, for example, formaldehyde, acetaldehyde, glyoxal, glutaric aldehyde, benzaldehyde and the like.

All of the condensates of any of the aromatic hydroxyl compound with any of the aldehydes above can be used. Typical examples of the condensates include the condensates of formaldehyde with phenol, hydroquinone, catechol, pyrogallol, 2,7-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, alizarin, anthraflavic acid, or 1,4,5,8-tetrahydroxynaphthalene, pyrogallol-benzaldehyde condensates, phenol-benzaldehyde condensates, 2,3-dihydroxynaphthalene-benzaldehyde condensates, catechol-benzaldehyde condensates, anthraflavic acid-benzaldehyde condensates, 2,7-dihydroxynaphthalene-benzaldehyde condensates, 1,4,5,8-tetrahydroxynaphthalene-benzaldehyde condensates, 1,5-dihydroxynaphthalene-benzaldehyde condensates and the like.

The condensate can be obtained by reacting an aromatic hydroxyl compound and an aldehyde in the presence of a catalyst in an aqueous or alcoholic solvent around room temperature to about 200° C. The catalyst includes, for example, acidic substances such as phosphoric acid and hydrochloric acid, and alkaline substances such as sodium hydroxide, potassium hydroxide and ammonia.

(C-3-4) Aromatic hydroxyl compound-aromatic amine compound condensates

The aromatic amine compound which is used as one of the reactants for the condensate, is exemplified by those described as the component (A) above.

The combination of an aromatic hydroxyl compound and an aromatic amine compound is not particularly limited. Typical examples include pyrogallol-p-phenylenediamine condensates, resorcinol-m-phenylenediamine condensates, pyrogallol-1,8-diaminonaphthalene condensates, catechol-1,8-diaminonaphthalene condensates, 2,7-dihydroxynaphthalene-p-aminophenol condensates, 4-aminodiphenylamine-pyrogallol condensates, and 2,3-dihydroxynaphthalene-1,5-diaminonaphthalene condensates.

The condensate can be obtained by reacting an aromatic hydroxyl compound and an aromatic amine compound at a temperature of about room temperature to about 200° C. in the presence of a catalyst in water, an organic solvent such as alcohols, ketones and esters, or a mixed solvent of water and an organic solvent mentioned above. The catalyst used includes, for example, peroxides such as periodic acid, potassium periodate and hydrogen peroxide, azo compounds such as α,α'-azobisisobutyronitrile, metallic salts such as ferric chloride, aromatic nitro compounds such as nitrobenzene, and aromatic quinone compounds such as p-benzoquinone.

(C-3-5) Natural aromatic hydroxyl-containing organic compound

The natural aromatic hydroxyl-containing organic compounds include, for example, Chinese gallotannin, sumac tannin, tara tannin, valonia tannin, chestnut tannin, myrobalan tannin, oak tannin, divi-divi tannin, algarobillatannin, gambier tannin, quebrachotannin, wattle tannin, mimosa tannin, mangrove tannin, hemlock tannin, spruce tannin, Burma cutch tannin, oak bark tannin, tannin of persimmon, curcumin, urushiol, lignin, sodium lignin sulfonate, alkali lignin and the like.

(C-3-6) Natural flavonoid hydroxyl-containing organic compounds

The natural flavonoid hydroxyl-containing organic compounds include, for example, pigments of Perilla frutescens, pigments of grape juice, pigment of grape skin, pigments of red cabbage, pigments of corn, pigments of koaliang, pigments of safflower, and pigment of cacao.

Among the aromatic hydroxyl compound-based condensates above, preferred are pyrogallol-acetone condensates, 2,7-dihydroxynaphthalene-acetone condensates, 2,3-dihydroxynaphthalene-acetone condensates, resorcinol-acetone condensates, 2,7-dihydroxynaphthalene-benzaldehyde condensates, 2,3-dihydroxynaphthalene-formaldehyde condensates, 1,4,5,8-tetrahydroxynaphthalene-benzaldehyde condensates, pyrogallol-formaldehyde condensates, 2,7-dihydroxynaphthalene condensates, pyrogallol condensates, 2,7-dihydroxynaphthalene-p-aminophenol condensates, catechol-4-aminodiphenylamine condensates, pyrogallol-1,8-diaminonaphthalene condensates, nutgalls tannin, wattle tannin, mimosa tannin, oak tannin, Chinese gallotannin, quebrachotannin, chestnut tannin, tannin of persimmon, and mangrove tannin.

The reaction stoppers (C) above can be used singly or in combination of two or more.

The reaction stopper (C) may be added to the reaction mixture after the condensation reaction of the components (A) and (B) is initiated, and preferably the reaction stopper (C) is added to the reaction mixture just before a condensation product of the components (A) and (B) precipitates, that is, at the time when the condensation conversion of the components (A) and (B) has reached a value in the range of 50 to 99% by weight, particularly 70 to 95% by weight. When a reaction stopper is added to the reaction mixture, the condensation reaction is almost stopped. Nevertheless, after the addition of the reaction stopper (C), the reaction system is normally maintained at the reaction temperature under stirring for 0 to 50 hours.

Condensation conversion of the components (A) and (B) herein means the total amount in % by weight of the components (A) and (B) consumed for the condensation based on the total amount of the components (A) and (B) charged as monomers. That is, condensation conversion of the components (A) and (B) is defined by the equation:

    Condensation conversion (% by weight)=[(a-b)/a]×100

wherein a stands for the total amount in part(s) by weight of the components (A) and (B) charged as monomers, and b stands for the total amount in part(s) by weight of the unreacted components (A) and (B).

It normally takes 0.1 to 80 hours for the condensation conversion of the components (A) and (B) to reach 50 to 99% by weight, although the time depends on the kinds of the components (A) and (B), etc.

Where the reaction stopper (C) is added to the reaction mixture, the preferred amount of the reaction stopper (C) is in the range of 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight per part by weight of the components (A) and (B) in total.

Polymer scale preventive agent comprising an alkaline solution containing the condensation product of components (A) and (B)

The polymer scale preventive agent of the present invention comprises an alkaline solution of the condensation product of the components (A) and (B), which is used for forming a coating on, for example, the inner wall surfaces of a polymerization vessel, and the deposition of polymer scale is thereby prevented.

For example, the polymer scale preventive agent may be prepared by, optionally, adding a solvent described below as required to a solution containing the condensation product of the components (A) and (B) resulting from the condensation reaction, and adjusting pH value. Alternatively, it may be prepared by adding the solution containing the condensation product into a cold water to allow the condensation product to form sediment, filtering off and drying the sediment, adding a solvent described below to the dried sediment, and adjusting pH value.

Since the polymer scale preventive agent of the present invention is made alkaline as described above, the solubility of the condensation product of the components (A) and (B) in a solvent is increased and the solution is made uniform, so that its polymer scale preventing effect is enhanced when coated on the inner wall, etc. of a polymerization vessel. The pH of the polymer scale preventive agent of the present invention is preferably in the range of 7.5 to 13.5, more preferably 8.0 to 12.5. As an alkaline compound to be used for adjusting pH, for example, alkali metal compounds such as LiOH, NaOH, KOH, Na₂ CO₃, Na₂ HPO₄, NH₄ OH and the like, ammonium compounds, and organic amine compounds such as ethylenediamine, monoethanolamine, triethanolamine and the like, can be used.

Solvents to be used for preparation of the polymer scale preventive agent include, for example, water; alcohols such as methanol, ethanol, propanol, butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 2-pentanol, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl acetoacetate, etc.; ethers such as 4-methyldioxolane, ethylene glycol diethyl ether, etc.; furans such as tetrahydrofuran, furfural, furfuryl alcohol, and tetrahydrofurfuryl alcohol; and aprotic solvents such as acetonitrile, dimethylformamide and dimethyl sulfoxide. These solvents may be used singly or as a mixed solvent of two or more thereof in a case-by-case basis.

Among the solvents above, particularly preferred are water, and mixed solvents of water and an organic solvent compatible with water. The organic solvent compatible with water includes, for example, alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, and esters such as methyl acetate and ethyl acetate. The mixed solvents of water and an organic solvent compatible with water preferably contains the organic solvent in such an amount that there is no fear about ignition or explosion and safety in handling is ensured as to virulence, etc. Specifically, the amount of the organic solvent is preferably 50% by weight or less, and more preferably 30% by weight or less.

The concentration of the condensation product of the components (A) and (B) in the alkaline solution is not limited as long as a total coating weight described later can be obtained. Normally, the concentration is in the range of about 0.001 to about 5% by weight, preferably 0.01 to 1% by weight.

In order to further enhance the scale preventive effect, to the polymer scale preventive agent described above is preferably added (D) a water-soluble polymeric compound and/or (E) at least one compound selected from the group consisting of a colloidal silica and an alkali metal silicate. More preferably, the (D) and (E) are used in combination. Presumably, these additives interact with the condensation product of the components (A) and (B), so that the component (D) improves hydrophilic nature of the surface of the coating and the component (E) increases the adhesion of the coating to the inner wall, etc. of the polymerization vessel.

(D) Water-soluble Polymeric Compound

The water-soluble polymeric compounds include, for example, amphoteric polymeric compounds such as gelatin and casein, anionic polymeric compounds such as polyacrylic acid, polystyrenesulfonic acid, carboxymethyl cellulose, and alginic acid, cationic polymeric nitrogen-containing polymeric compounds such as polyvinylpyrrolidone and polyacrylamide, hydroxyl-containing polymeric compounds such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose and pectin.

Among the water-soluble polymeric compounds above, preferred are gelatin, casein, polyacrylic acid, carboxymethyl cellulose, polyvinylpyrrolidone and pectin.

The amount of the water-soluble polymeric compound (D) is preferably in the range of 0.01 to 10 parts by weight, and more preferably from 0.05 to 2 parts by weight per part by weight of the condensation product of the components (A) and (B).

(E) At Least One Compound Selected From The Group Consisting Of Colloidal Silica And Alkali Metal Silicate

Colloidal silica is a colloid in which ultrafine particles of silicon dioxide (silica) are dispersed in an aqueous medium or a non-aqueous medium such as methanol, propanol, ethylene glycol, or the like. The colloidal particles generally have a particle diameter of 1 to 100 mμ.

It is well-known that colloidal silica, for example, dispersed in an aqueous medium can be typically produced by adding hydrochloric acid to an aqueous sodium silicate solution, but production methods are not limited thereto. Any production methods can be used as long as the colloidal silica described above is produced.

The silicates of alkali metals include, for example, metasilicates (M₂ SiO₃), orthosilicates (M₄ SiO₄), bisilicates (M₂ Si₂ O₅), trisilicates (M₃ Si₃ O₇) and sesquisilicates (M₄ Si₃ O₁₀) of alkali metals such as lithium, sodium and potassium (where M stands for an alkali metal such as lithium, sodium or potassium), and water glass.

The amount of the component (E) is preferably in the range of 0.01 to 10 parts by weight, more preferably from 0.05 to 5 parts per part by weight of the condensation product of the components (A) and (B).

The water-soluble polymeric compound (D) may be added without any component (E), but it is preferably combined with the colloidal silica and/or the alkali metal silicate (E). Where the water-soluble polymeric compound is used in combination with the colloidal silica, the colloidal silica is used in an amount of preferably 5 to 3,000 parts by weight, more preferably 50 to 1,000 parts by weight per 100 parts by weight of the water-soluble polymeric compound. Where the water-soluble polymeric compound is used in combination with the alkali metal silicate, the alkali metal silicate is used in an amount of preferably 5 to 3,000 parts by weight, more preferably 50 to 1,000 parts by weight per 100 parts by weight of the water-soluble polymeric compound.

Furthermore, the polymer scale preventive agent may optionally contains one or more inorganic colloids other than the colloidal silica mentioned above, including, for example, gold colloid, silver colloid, silver iodide sol, selenium colloid, sulfur colloid, and colloids of oxides of metals such as, e.g., aluminum, thorium, titanium, antimony, tin and iron.

Formation of the coating

The polymer scale preventive agent is applied to the inner walls of a polymerization vessel and then dried sufficiently at a temperature from room temperature to 100° C., for instance, followed by washing with water if necessary, to form the coating.

The polymer scale preventive agent is preferably applied to not only the inner wall surfaces of a polymerization vessel but also other areas with which the monomer comes into contact during polymerization to form the coating on such areas. For example, on a stirring shaft, stirring blades, condensers, headers, search coil, bolts, nuts, etc.

More preferably, for formation of the coating, the polymer scale preventive agent is applied to areas with which monomers does not come into contact during polymerization but on which polymer scale may deposit, for example, the areas with which unreacted monomers comes into contact of an unreacted monomer recovery system; specifically the inner surfaces, etc. of equipment and pipes of the recovery system. Specifically, such areas include the inner surfaces of monomer distillation columns, condensers, monomer stock tanks and valves.

The method of applying the scale preventing agent is not particularly limited, and includes, for example, the brush coating, spray coating, the method of filing the polymerization vessel with the coating solution followed by withdrawal thereof, and automatic coating methods as disclosed in Japanese Pre-examination Patent Publication (KOKAI) Nos. 57-61001(1982) and 55-36288(1980), and Japanese Patent Publication (KOHYO) Nos. 56-501116(1981) and 56-501117(1981), and Japanese Pre-examination Publication (KOKAI) No. 59-11303(1984), etc.

The method of drying wet coated surfaces provided by application of the polymer scale preventive agent, is not limited, either. Following methods can be used. That is, a method in which, after the solution is applied, hot air with an suitable elevated temperature is blown to the coated surface, and a method in which the inner wall surface of a polymerization vessel and the surfaces of other parts to be coated are previously heated to from 30° to 80° C., and the polymer scale preventive agent is directly applied to the heated inner wall surfaces, etc. After dried, the coated surfaces are washed with water if necessary.

The coating thus obtained normally has a coating weight of normally 0.001 g/m² to 5 g/m², and preferably from 0.05 to 2 g/m².

The coating operation may be conducted every one to ten-odd batches of polymerization. The formed coating has good durability and retains the scale-preventing action; therefore the coating operation may be performed every several batches of polymerization. Thus, the polymerization vessel can be used repeatedly without deposition of polymer scale, and productivity is improved.

Polymerization

After the formation of the coating on the inner wall surfaces of a polymerization vessel, and preferably other parts with which monomer may come into contact during polymerization, polymerization is carried out in accordance with conventional procedures. That is, a monomer having an ethylenically unsaturated double bond, a polymerization initiator, and optionally a polymerization medium such as water, etc., a suspending agent, a solid dispersing agent, a dispersing agent such as nonionic or anionic surfactants are charged into the polymerization vessel, followed by carrying out polymerization according to conventional methods.

The monomer having an ethylenically unsaturated double bond to which of this invention can be applied may include, for example, vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid, methacrylic acid, and esters or salts thereof; maleic acid, fumaric acid, and esters or salts thereof; and diene monomers such as butadiene, chloroprene and isoprene; styrene, acrylonitrile, vinylidene halides such as vinylidene chloride, and vinyl ethers. These may be used singly or in combination of two or more.

There are no particular limitations on the type of polymerization to which this invention can be applied. The present invention is effective in any type of polymerization such as suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, and gas phase polymerization. Particularly, the present invention is more suitable to polymerizations in an aqueous medium such as suspension or emulsion polymerization.

In the following, general conditions are described on each type of polymerizations.

In the case of suspension or emulsion polymerization, first, water and a dispersing agent are charged into a polymerization vessel, and thereafter a polymerization initiator is charged. Subsequently, the inside of the polymerization vessel is evacuated to a pressure of from 0.1 to 760 mmHg, and a monomer is then charged (whereupon the pressure inside the polymerization vessel usually becomes from 0.5 to 30 kgf/cm².G). Thereafter, polymerization is carried out at a temperature of from 30° to 150° C. During the polymerization, one or more of water, a dispersing agent and a polymerization initiator may be added, if necessary. Reaction temperature during the polymerization is different depending on the kind of monomer to be polymerized. For example, in the case of polymerizing vinyl chloride, polymerization is carried out at 30° to 80° C.; in the case of polymerizing styrene, polymerization is carried out at 50° to 150° C. The polymerization may be judged to be completed when the pressure inside the polymerization vessel falls to from 0 to 7 kgf/cm².G or when cooling water which passes through a jacket provided around the polymerization vessel indicates almost the same temperature at the inlet where it is charged and at the outlet where it is discharged (i.e., when liberation of heat due to polymerization reaction has subsided). The water, dispersing agent and polymerization initiator to be charged for polymerization are used in amounts of 20 to 500 parts by weight, 0.01 to 30 parts by weight, and 0.01 to 5 parts by weight, respectively, per 100 parts by weight of the monomer.

In the case of solution polymerization, an organic solvent such as toluene, xylene and pyridine is used as the polymerization medium in place of water. The dispersing agent is optionally used. The other conditions are generally the same as those described for suspension and emulsion polymerizations.

In the case of bulk polymerization, after the inside of a polymerization vessel is evacuated to a pressure of from about 0.01 mmHg to about 760 mmHg, a monomer and a polymerization initiator are charged into the polymerization vessel, and then polymerization is carried out at a temperature of from -10° C. to 250° C. Specific methods of the bulk polymerization includes, for example, liquid bulk polymerization and gas phase polymerization.

The present invention makes it possible to prevent polymer scale from depositing, independent of materials constituting the inner wall, etc. of a polymerization vessel. For example, this invention can prevent deposition of polymer scale even in the case polymerization is carried out in a polymerization vessel made of a steel including stainless steel or lined with glass.

Any additive materials that have been conventionally added in a polymerization system can be used without any limitation. More specifically, the method of this invention can effectively prevent polymers from depositing, even in polymerization systems containing the following additives: for example, polymerization catalysts such as t-butyl peroxyneodecanoate, bis(2-ethylhexyl) peroxydicarbonate, 3,5,5-trimethylhexanoyl peroxide, α-cumyl peroxyneodecanoate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl peroxypivalate, bis(2-ethoxylhexyl) peroxydicarbonate, benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, α,α'-azobisisobutyronitrile, α,α'-azobis-2,4-dimethylvaleronitrile, potassium peroxodisulfate, ammonium peroxodisulfate, and p-menthane hydroperoxide; suspension agents comprised of natural or synthetic polymeric compounds such as partially saponified polyvinyl alcohols, polyacrylic acids, vinyl acetate/maleic anhydride copolymers, cellulose derivatives such as hydroxypropylmethyl cellulose, and gelatin; solid dispersing agents such as calcium phosphate and hydroxyapatite; nonionic emulsifying agents such as sorbitan monolaurate, sorbitan trioleate and polyoxyethylene alkyl ether; anionic emulsifying agents such as sodium lauryl sulfate, sodium alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate and sodium dioctylsulfosuccinate; fillers such as calcium carbonate and titanium oxide; stabilizers such as tribasic lead sulfate, calcium stearate, dibutyltin dilaurate and dioctyltin mercaptide; lubricants such as rice wax, stearic acid and cetyl alcohol; plasticizers such as DOP and DBP; chain transfer agents such as mercaptans such as t-dodecyl mercaptan, and trichloroethylene; and pH adjusters.

Addition to polymerization mass

The polymer scale preventive agent of the present invention may be added to a polymerization mass in addition to the formation of the coating, so that the scale preventing effect is further improved. The amount of the polymer scale preventive agent to be added to the polymerization mass preferably in the range of about 10 to about 1,000 ppm based on the whole weight of the monomers charged. The polymer scale preventive agent is normally added in the form of liquid like the polymer scale preventive agent described above, although the form thereof is not limited. The addition should be conducted so that it may not adversely affect the quality of polymeric products to be obtained with respect to fish eyes, bulk density, particle size distribution, etc.

EXAMPLES

The working examples of the present invention and comparative examples will now be described below. In each table below, experiments marked with * are comparative examples and the other experiments are working examples of the present invention.

Production Example 1

Production of Condensation Product No.1

An autoclave was charged with 980 g of methanol and 10 g of 1,8-diaminonaphthalene as the aromatic amine compound (A-2), and they were stirred, so that the 1,8-diaminonaphthalene was dissolved in the methanol.

The methanol solution thus obtained was added with 1 g of p-benzoquinone as the quinone compound (B), and the mixture obtained was heated to 50° C., subjected to reaction at 50° C. for 5 hours, and then cooled. Thus, a methanol solution of Condensation Product No.1 was obtained.

Production of Condensation Product Nos.2-15

In each production, the procedure of Production Condensation Product No.1 was repeated, except for using an aromatic amine compound (A-2) and a quinone compound (B) given in Table 1 and a solvent given in Table 2 under conditions given in Table 2 (total concentration, (A-1):(A-2):(B) ratio, reaction temperature and reaction time). Thus, Condensation Product Nos.2 to 15 were obtained.

Production of Condensation Product No.16(control)

In accordance with Japanese Patent Publication (kokoku) No.60-30681(1985), a condensation product of aniline and nitrobenzene named the condensation product No.1 was reproduced. The product obtained is herein referred to Condensation Product No.16.

Production of Condensation Product No.17(control)

In accordance with Japanese Pre-examination Patent Publication (kokai) No.61-7309(1986), particularly Production Example 8 of Experiment 12 in Example 1, a condensation product of 1,8-diaminonaphthalene and β-naphthoquinone was reproduced. The product obtained is herein referred to Condensation Product No.17.

                  TABLE 1                                                          ______________________________________                                         Conden-                                                                        sation                                                                         product                                                                               (A) Aromatic amine compound                                                                        (B)                                                 No.    (A-1)   (A-2)           Quinone compound                                ______________________________________                                         1      --      1,8-Diaminonaphthalene                                                                         p-Benzoquinone                                   2*    --      1,8-Diaminonaphthalene                                                                         --                                               3*    --      --              p-Benzoquinone                                  4      --      α-Naphthylamine                                                                          p-Benzoquinone                                  5      --      β-Naphthylamine                                                                           p-Benzoquinone                                  6      --      1,5-Diaminonaphthalene                                                                         p-Benzoquinone                                  7      --      2,3-Diaminonaphthalene                                                                         p-Benzoquinone                                  8      --      1,8-Diaminonaphthalene                                                                         Lawson                                          9      --      1,8-Diaminonaphthalene                                                                         o-Benzoquinone                                  Naphthylamine  α                                                                Juglone                                                                 Naphthylamine  α                                                                α-Naphthoquinone                                                  Naphthylamine  β                                                                 β-Naphthoquinone                                                   13     --      1,8-Diaminonaphthalene                                                                         α-Naphthoquinone                          14     --      1,8-Diaminonaphthalene                                                                         Hydroxy-p-                                                                     benzoquinone                                    15     --      1,8-Diaminonaphthalene                                                                         Duroquinone                                     ______________________________________                                    

                                      TABLE 2                                      __________________________________________________________________________     Conden-       Total conc.                                                      sation        of             Reaction -                                                                            Reaction                                   product                                                                             Solvent  (A-2) + (B)                                                                           (A-1):(A-2):(B)                                                                        temperature                                                                           time                                       No.  (wt. ratio)                                                                             (wt. %)                                                                               (wt. ratio)                                                                            (°C.)                                                                          (Hr)                                       __________________________________________________________________________     1    Methanol 1.1    --:100:10                                                                              50     5                                           2*  Methanol 1.1    --      50     5                                           3*  Methanol 1.1    --      50     5                                          4    Methanol 2.0    --:100:5                                                                               50     5                                          5    Methanol:Water                                                                          2.0    --:100:10                                                                              30     10                                              (50:50)                                                                   6    Methanol:Water                                                                          2.0    --:100:10                                                                              30     50                                              (70:30)                                                                   7    Methanol 2.0    --:100:20                                                                              70     3                                          8    Methanol 1.0    --:100:30                                                                              100    1                                          9    Methanol 1.0    --:100:5                                                                               100    0.5                                        10   Methanol 1.0    --:100:20                                                                              80     2                                          11   Methanol:Water                                                                          3.0    --:100:5                                                                               150    0.5                                             (80:20)                                                                   12   Methanol 1.5    --:100:10                                                                              30     20                                         13   Methanol 2.0    --:100:20                                                                              50     5                                          14   Methanol 2.0    --:100:50                                                                              25     20                                         15   Methanol 1.1    --:100:60                                                                              40     10                                         __________________________________________________________________________

Example 1 (Experiment Nos. 101 to 118)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 1,000 liters and having a stirrer, as described below.

First, a polymer scale preventive agent as shown in Table 3 (solvent composition, concentration and pH was prepared using a condensation product, a solvent and alkaline compound given in Table 3. The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

Thereafter, into the polymerization vessel in which the coating was formed as above, 400 kg of water, 200 kg of vinyl chloride, 250 g of a partially saponified polyvinyl alcohol, 25 g of hydroxypropyl methyl cellulose and 70 g of 3,5,5-trimethylhexanoyl peroxide were charged, followed by polymerization at 66° C. for 6 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 5 times. After the 5th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured according the method below.

--Measurement of the amount of polymer scale

The scale deposited in an area of 10 cm square on the inner wall is scraped off with a stainless steel spatula as completely as possible to be confirmed with naked eyes, and then the scraped scale is weighted on a balance. Thereafter, the amount of the deposited scale per area of 1 m² is obtained by multiplying the measured value by 100.

The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments according to the method below.

--Measurement of fish eves

A hundred parts by weight of a polymer, 50 parts by weight of dioctyl phthalate (DOP), 1 part by weight of dibutyltin dilaurate, 1 part by weight of cetyl alcohol, 0.25 part by weight of titanium oxide and 0.05 part by weight of carbon black are formulated to prepare a mixture. The mixture is kneaded at 150° C. for 7 minutes with 6 inch rolls, and then formed into a sheet 0.2 mm thick. The sheet is examined for the number of fish eyes per 100 cm² by light transmission.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured according to the method below.

--Measurement of luminosity index L

A hundred parts by weight of a polymer, 1 part by weight of a tin laurate stabilizing agent (trade name: TS-101, product of Akisima Chemical Co.) and 0.5 part by weight of cadmium stabilizing agent (trade name: C-100J, product of Katsuta Kako Co.), and 50 parts by weight of DOP are kneaded at 160° C. for 5 minutes with a twin roll mill, and then formed into a sheet 1 mm thick. Subsequently, this sheet is placed in a mold measuring 4 cm×4 cm×1.5 cm (depth), and molded under heating at 160° C. and a pressure of 65 to 70 kgf/cm² to prepare a test specimen. This test specimen is measured for luminosity index L in the Hunter's color difference equation described in JIS Z 8730 (1980). The lower initial coloration, the more the value of L.

The value of L was determined as follows. The stimulus value Y of XYZ color system is determined according to the photoelectric tristimulus colorimetry using the standard light C, photoelectric colorimeter (Color measuring color difference meter Model Z-1001DP, product of Nippon Denshoku Kogyo K.K.) in accordance with JIS Z 8722. As the geometric condition for illumination and being illuminated, the condition d defined in section 4.3.1 of JIS Z 8722 is adopted. Next, L is calculated based on the equation: L=10Y^(1/2) described in JIS Z 8730 (1980).

The results are given in Table 4.

                                      TABLE 3                                      __________________________________________________________________________     Polymer scale preventive agent                                                     Condensation       Concen-                                                 Exp.                                                                               product                                                                               Solvent     tration                                                 No. No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                       __________________________________________________________________________     101 1      Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          9.5                                       102*                                                                              2      Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          9.5                                       103*                                                                              3      Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          9.5                                      104 4      Water:Methanol (90:10)                                                                     0.2  NaOH      9.5                                      105 5      Water:Methanol (90:10)                                                                     0.2  KOH       9.0                                      106 6      Water:Methanol (70:30)                                                                     0.1  Triethanolamine                                                                          9.0                                      107 7      Water:Methanol (80:20)                                                                     0.3  NaOH      10.0                                     108 8      Water:Methanol (80:20)                                                                     0.1  Monoethanolamine                                                                         10.0                                     109 9      Water:Methanol (80:20)                                                                     0.05 NH.sub.4 OH                                                                              10.0                                     110 10     Water:Methanol (80:20)                                                                     0.1  LiOH      11.0                                     111 11     Water:Methanol (80:20)                                                                     0.2  Na.sub.2 CO.sub.3                                                                        11.0                                     112 12     Water:Methanol (80:20)                                                                     0.2  NaOH      11.5                                     113 13     Water:Methanol (90:10)                                                                     0.2  Ethylenediamine                                                                          12.0                                     114 14     Water:Methanol (70:30)                                                                     0.3  NaOH      12.5                                     115 15     Water:Methanol (70:30)                                                                     0.5  KOH       12.0                                      116*                                                                              16     Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          9.5                                       117*                                                                              17     DMAC:Acetone (80:20)                                                                       0.3  --        6.0                                       118*                                                                              1      Water:Methanol (80:20)                                                                     0.2  --        6.0                                      __________________________________________________________________________      DMAC: Dimethylacetamide                                                  

                  TABLE 4                                                          ______________________________________                                         Results after 5th polymerization batch                                         Scale amount (g/m.sup.2)                                                                              No. of                                                  Exp.   Liquid  Around interface of                                                                            fish  L                                         No.    phase   gas-liquid phases                                                                              eyes  value                                     ______________________________________                                         101    0       8               7     72.6                                       102*  54      530             30    72.3                                       103*  62      610             33    72.8                                      104    0       8               7     72.6                                      105    0       9               8     72.6                                      106    0       8               7     72.7                                      107    0       8               8     72.5                                      108    0       9               8     72.7                                      109    0       20              10    72.8                                      110    0       9               7     72.7                                      111    0       9               8     72.7                                      112    0       10              8     72.7                                      113    0       9               8     72.6                                      114    0       9               9     72.5                                      115    0       7               10    72.3                                       116*  0       360             30    69.8                                       117*  7       280             29    71.3                                       118*  5       120             27    71.4                                      ______________________________________                                    

Example 2 (Experiment Nos. 201 to 116)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

First, a polymer scale preventive agent as shown in Table 5 (solvent composition, concentration and pH) was prepared using a condensation product, solvent and alkaline compound given in Table 5. The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

Thereafter, into the polymerization vessel in which the coating was formed as above, 9 kg of water, 225 g of sodium dodecylbenzenesulfonate, 12 g of t-dodecyl mercaptan and 13 g of potassium peroxodisulfate were charged. After the inside of the polymerization vessel was replaced with a nitrogen gas, 1.3 kg of styrene and 3.8 kg of butadiene were charged, followed by polymerization at 50° C. for 20 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch comprising the operations from forming a coating through polymerizing to washing with water was repeated 3 times. After the 3th batch, the amount of polymer scale on an area located in the liquid during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured according to the method below.

The results are given in Table 6.

--Measurement of luminosity index L

To 1 kg of a polymer latex obtained was added 1 kg of 2% magnesium sulfate solution to cause aggregation and sedimentation. The sediment was filtered off, washed with a hot water at 80° to 90° C. twice or three times and dried at 40° C. for 25 hours in a vacuum dryer to give a resin. The resin was placed in a mold measuring 9×9×0.1 cm (depth), heated at 195° C. under a pressure of 50 to 60 kgf/cm² and press molded under the final pressure of 80 kgf/cm² to prepare a test specimen.

This test specimen was measured for luminosity index L in the same manner as in Example 1.

                                      TABLE 5                                      __________________________________________________________________________     Polymer scale preventive agent                                                     Condensation       Concen-                                                 Exp.                                                                               product                                                                               Solvent     tration                                                 No. No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                       __________________________________________________________________________     201 1      Water:Methanol (80:20)                                                                     0.3  Ethylenediamine                                                                          9.5                                       202*                                                                              2      Water:Methanol (80:20)                                                                     0.3  Ethylenediamine                                                                          9.5                                       203*                                                                              3      Water:Methanol (80:20)                                                                     0.3  Ethylenediamine                                                                          9.5                                      204 4      Water:Methanol (70:30)                                                                     0.3  Triethanolamine                                                                          9.5                                      205 5      Water:Methanol (90:10)                                                                     0.2  NaOH      10.0                                     206 6      Water:Methanol (90:10)                                                                     0.2  KOH       10.0                                     207 7      Water:Methanol (80:20)                                                                     0.2  NaOH      10.5                                     208 8      Water:Methanol (80:20)                                                                     0.2  Monoethanolamine                                                                         10.5                                     209 9      Water:Methanol (80:20)                                                                     0.1  LiOH      11.0                                     210 10     Water:Methanol (80:20)                                                                     0.05 NH.sub.4 OH                                                                              11.0                                     211 11     Water:Methanol (80:20)                                                                     0.2  KOH       12.0                                     212 12     Water:Methanol (70:30)                                                                     0.2  NaOH      12.5                                     213 13     Water:Methanol (70:30)                                                                     0.2  Triethanolamine                                                                          10.5                                     214 14     Water:Methanol (70:30)                                                                     0.2  Monoethanolamine                                                                         10.5                                     215 15     Water:Methanol (70:30)                                                                     0.3  Ethylenediamine                                                                          10.5                                      216*                                                                              1      Water:Methanol (80:20)                                                                     0.3  --        6.0                                      __________________________________________________________________________

                  TABLE 6                                                          ______________________________________                                                 Results after 3rd polymerization batch                                         Scale amount (g/m.sup.2)                                               Exp.    Liquid      Around interface of                                                                          L                                            No.     phase       gas-liquid phases                                                                            value                                        ______________________________________                                         201     0           10            85.5                                          202*   15          310           84.7                                          203*   47          510           85.7                                         204     0           12            85.5                                         205     0           16            85.5                                         206     0           15            85.5                                         207     0           11            85.6                                         208     0           13            85.5                                         209     0           16            85.6                                         210     0           18            85.7                                         211     0           14            85.5                                         212     0           15            85.5                                         213     0           15            85.5                                         214     0           12            85.5                                         215     0           10            85.5                                          216*   12          130           84.4                                         ______________________________________                                    

Production Example 2

Production of Condensation Product No.18

An autoclave was charged with 490 g of methanol and 5 g of 3,5-diaminobenzoic acid as the aromatic amine compound (A-1) and 5 g of p-benzoquinone as the quinone compound (B), and they were heated to 30° C. subjected to reaction at 30° C. for 20 hours, and then cooled. Thus, a solution of Condensation Product No.18 was obtained.

Production of Condensation Product Nos.19-43

In each production, the procedure of Production Condensation Product No.18 was repeated, except for using an aromatic amine compound (A-1) or (A-2) and a quinone compound (B) given in Table 7 and a solvent given in Table 8 under conditions given in Table 8 (total concentration, (A-1):(A-2):(B) ratio, reaction temperature and reaction time). Thus, Condensation Product Nos.19 to 43 were obtained.

                                      TABLE 7                                      __________________________________________________________________________     Condensation                                                                   product                                                                               (A) Aromatic amine compound                                                                            (B) Quinone                                     No.    (A-1)       (A-2)       compound                                        __________________________________________________________________________     18     3,5-Diaminobenzoic acid                                                                    --          p-Benzoquinone                                  19     1,5-Naphthylenediamine-                                                                    --          p-Benzoquinone                                         2-carboxylic acid                                                       20     2,5-Diaminoterephthalic                                                                    --          Bromo-p-                                               acid                    benzoquinone                                    21     3,4-Diaminobenzoic acid                                                                    --          Lawson                                          22     4,6-Diaminobenzoic acid                                                                    --          α-Naphtoquinone                           23     3,5-Diaminobenzoic acid                                                                    --          Plumbagin                                       24     2,5-Diaminobenzene-                                                                        --          p-Benzoquinone                                         sulfonic acid                                                           25     1,2-Naphthylenediamine-                                                                    --          Duroquinone                                            7-sulfonic acid                                                         26     1,5-Naphthylenediamine-                                                                    --          β-Naphthoquinone                                  4-sulfonic acid                                                         27     1,6-Naphthylenediamine-                                                                    --          Lawson                                                 4-sulfonic acid                                                         28     2,4-Diaminobenzene-                                                                        --          α-Naphthoquinone                                 sulfonic acid                                                           29     p-Aminophenol                                                                              --          p-Benzoquinone                                  30     p-Aminosalicylic acid                                                                      --          p-Benzoquinone                                  31     p-Aminophenol                                                                              --          α-Naphthoquinone                          32     2,5-Diaminobenzoic acid                                                                    --          α-Naphthoquinone                          33     p-Aminobenzenesulfonic                                                                     --          α-Naphthoquinone                                 acid                                                                    34     p-Aminosalicylic acid                                                                      --          Juglone                                         35     m-Aminophenol                                                                              --          Lawson                                          36     2-Naphthylamine-1-                                                                         --          Bromo-p-                                               sulfonic acid           benzoquinone                                    37     o-Aminophenol                                                                              --          p-Benzoquinone                                  38     2-Amino-1-phenol-4-                                                                        --          p-Benzoquinone                                         sulfonic acid                                                           39     p-Aminophenol                                                                              --          o-Benzoquinone                                  40     o-Aminophenol                                                                              --          p-Toluquinone                                   41     m-Aminophenol                                                                              --          Duroquinone                                     42     --          1,8-Diaminonaphthalene                                                                     p-Benzoquinone                                  43     --          m-Phenylenediamine                                                                         Lawson                                          __________________________________________________________________________

                                      TABLE 8                                      __________________________________________________________________________     Conden-       Total conc.                                                      sation        of             Reaction                                                                              Reaction                                   product                                                                             Solvent  (A-1) + (B)                                                                           (A-1):(A-2):(B)                                                                        temperature                                                                           time                                       No.  (wt. ratio)                                                                             (wt. %)                                                                               (wt. ratio)                                                                            (°C.)                                                                          (Hr)                                       __________________________________________________________________________     18   Methanol 2.0    100:--:100                                                                             30     20                                         19   Methanol 2.0    100:--:50                                                                              30     40                                         20   Methanol 2.0    100:--:100                                                                             50     30                                         21   Methanol:Water                                                                          4.0    100:--:100                                                                             50     10                                              (70:30)                                                                   22   Methanol 2.0    100:--:150                                                                             60     15                                         23   Methanol 1.0    100:--:10                                                                              80     5                                          24   Methanol:Water                                                                          2.0    100:--:50                                                                              80     20                                              (50:50)                                                                   25   Methanol:Water                                                                          2.0    100:--:200                                                                             80     20                                              (70:30)                                                                   26   Methanol:Water                                                                          0.5    100:--:300                                                                             40     20                                              (70:30)                                                                   27   Methanol:Water                                                                          2.0    100:--:100                                                                             50     30                                              (70:30)                                                                   28   Methanol:Water                                                                          2.0    100:--:100                                                                             50     40                                              (50:50)                                                                   29   Methanol:Water                                                                          3.0    100:--:20                                                                              50     15                                              (95:5)                                                                    30   Methanol:Water                                                                          3.0    100:--:30                                                                              40     20                                              (95:5)                                                                    31   Methanol:Water                                                                          1.0    100:--:30                                                                              30     40                                              (90:10)                                                                   32   Methanol:Water                                                                          1.0    100:--:50                                                                              20     60                                              (80:20)                                                                   33   Methanol:Water                                                                          1.0    100:--:100                                                                             100    5                                               (60:40)                                                                   34   Methanol 2.0    100:--:50                                                                              40     25                                         35   Methanol 2.0    100:--:200                                                                             40     50                                         36   Methanol:Water                                                                          2.0    100:--:100                                                                             40     50                                              (50:50)                                                                   37   Methanol:Water                                                                          2.0    100:--:50                                                                              40     50                                              (95:5)                                                                    38   Methanol:Water                                                                          2.0    100:--:30                                                                              40     50                                              (60:40)                                                                   39   Methanol 2.5    100:--:20                                                                              30     50                                         40   Methanol 2.5    100:--:30                                                                              30     25                                         41   Methanol 3.0    100:--:50                                                                              100    0.5                                        42   Methanol 2.0    --:100:100                                                                             40     15                                         43   Methanol:Water                                                                          2.0    --:100:20                                                                              40     15                                              (80:20)                                                                   __________________________________________________________________________

Example 3 (Experiment Nos. 301 to 327)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 2,000 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 9 under conditions given in Table 9 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 1. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 20 times, except for Experiment No. 327. After the 20th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1. In Experiment of No.327 marked with *, the amount of polymer scale was measured after the 10th batch. The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 1.

The results are given in Table 10.

                                      TABLE 9                                      __________________________________________________________________________     Polymer scale preventive agent                                                     Condensation       Concen-                                                 Exp.                                                                               product                                                                               Solvent     tration                                                 No. No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                       __________________________________________________________________________     301 18     Water:Methanol (90:10)                                                                     0.3  NaOH      9.5                                      302 19     Water:Methanol (90:10)                                                                     0.3  NaOH      9.5                                      303 20     Water:Methanol (90:10)                                                                     0.3  NaOH      10.0                                     304 21     Water:Methanol (85:15)                                                                     0.2  Ethylenediamine                                                                          10.0                                     305 22     Water:Methanol (85:15)                                                                     0.4  KOH       8.5                                      306 23     Water:Methanol (85:15)                                                                     0.5  KOH       8.0                                      307 24     Water       0.5  Ethylenediamine                                                                          10.0                                     308 25     Water:Methanol (90:10)                                                                     0.2  NaOH      9.5                                      309 27     Water:Methanol (90:10)                                                                     0.4  NaOH      11.0                                     310 27     Water:Methanol (95:5)                                                                      0.3  Ethylenediamine                                                                          12.0                                     311 28     Water:Methanol (95:5)                                                                      0.3  NaOH      12.0                                     312 29     Water:Methanol (90:10)                                                                     0.3  NaOH      10.0                                     313 30     Water:Methanol (90:10)                                                                     0.3  NaOH      9.5                                      314 31     Water:Acetone (95:5)                                                                       0.4  KOH       9.0                                      315 32     Water:Methanol (90:10)                                                                     0.5  KOH       9.0                                      316 33     Water:Methanol (80:20)                                                                     0.2  KOH       9.0                                      317 34     Water:Methanol (80:20)                                                                     0.1  NaOH      8.5                                      318 35     Water:Methanol (80:20)                                                                     0.3  Ethylenediamine                                                                          11.0                                     319 36     Water:Methanol (90:10)                                                                     0.3  NaOH      12.0                                     320 37     Water:Methanol (90:10)                                                                     0.3  Ethylenediamine                                                                          12.5                                     321 38     Water:Methanol (90:10)                                                                     0.3  NaOH      12.5                                     322 39     Water:Methanol (80:20)                                                                     0.2  Triethanolamine                                                                          9.0                                      323 40     Water:Methanol (80:20)                                                                     0.2  NaOH      12.5                                     324 41     Water:Methanol (80:20)                                                                     0.2  NaOH      10.5                                     325 42     Water:Methanol (80:20)                                                                     0.2  NaOH      9.0                                      326 43     Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          9.5                                       327*                                                                              18     Water:Methanol (90:10)                                                                     0.3  --        5.5                                      __________________________________________________________________________      *After 10th polymerization batch.                                        

                  TABLE 10                                                         ______________________________________                                         Results after 20th polymerization batch                                        Scale amount (g/m.sup.2)                                                                              No. of                                                  Exp.   Liquid  Around interface of                                                                            fish  L                                         No.    phase   gas-liquid phases                                                                              eyes  value                                     ______________________________________                                         301    0        7              7     72.6                                      302    0       10              8     72.5                                      303    0        8              7     72.6                                      304    0        7              7     72.6                                      305    0        8              7     72.5                                      306    0       13              8     72.5                                      307    0       10              8     72.5                                      308    0        7              7     72.5                                      309    0        8              7     72.5                                      310    0       14              9     72.5                                      311    0       13              8     72.5                                      312    0        9              7     72.6                                      313    0       10              7     72.5                                      314    0        9              7     72.5                                      315    0        9              7     72.5                                      316    0       17              9     72.6                                      317    0       15              9     72.6                                      318    0       11              8     72.5                                      319    0       10              8     72.5                                      320    0       13              9     72.5                                      321    0       10              7     72.4                                      322    0       18              11    72.5                                      323    0       13              9     72.6                                      324    0       19              12    72.5                                      325    0       58              24    72.1                                      326    0       52              23    72.2                                       327*  18      105             26    71.1                                      ______________________________________                                           *After 10th polymerization batch.                                       

Example 4 (Experiment Nos. 401 to 422)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 11 under conditions given in Table 11 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 2. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 10 times. After the 10th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 2.

The results are given in Table 12.

                                      TABLE 11                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation       Concen-                                                  Exp.                                                                              product                                                                               Solvent     tration                                                  No.                                                                               No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                        __________________________________________________________________________     401                                                                               18     Water:Methanol (85:15)                                                                     0.3  NaOH      9.0                                       402                                                                               20     Water:Methanol (90:10)                                                                     0.3  Ethylenediamine                                                                          9.0                                       403                                                                               21     Water:Methanol (90:10)                                                                     0.05 KOH       10.0                                      404                                                                               22     Water:Methanol (90:10)                                                                     0.1  Triethanolamine                                                                          11.0                                      405                                                                               24     Water:Methanol (90:10)                                                                     0.3  NaOH      9.0                                       406                                                                               25     Water:Methanol (95:5)                                                                      0.3  Ethylenediamine                                                                          9.0                                       407                                                                               26     Water:Methanol (90:10)                                                                     0.3  NaOH      12.0                                      408                                                                               29     Water:Methanol (90:10)                                                                     0.3  NaOH      10.0                                      409                                                                               30     Water:Methanol (90:10)                                                                     0.3  KOH       10.0                                      410                                                                               31     Water:Methanol (90:10)                                                                     0.3  KOH       10.0                                      411                                                                               32     Water:Methanol (90:10)                                                                     0.1  KOH       9.0                                       412                                                                               33     Water:Methanol (90:10)                                                                     0.05 Ethylenediamine                                                                          11.0                                      413                                                                               34     Water:Methanol (90:10)                                                                     0.3  Monoethanolamine                                                                         12.0                                      414                                                                               35     Water:Ethanol (80:20)                                                                      0.5  NaOH      12.5                                      415                                                                               36     Water:Acetone (80:20)                                                                      0.3  Triethanolamine                                                                          12.0                                      416                                                                               37     Water:Methanol (80:20)                                                                     0.3  KOH       10.0                                      417                                                                               38     Water:Methanol (80:20)                                                                     0.3  KOH       10.0                                      418                                                                               39     Water:Methanol (80:20)                                                                     0.2  NaOH      9.5                                       419                                                                               40     Water:Methanol (80:20)                                                                     0.2  NaOH      9.5                                       420                                                                               41     Water:Methanol (90:10)                                                                     0.2  NaOH      10.5                                      421                                                                               42     Water:Methanol (90:10)                                                                     0.2  NaOH      10.5                                      422                                                                               43     Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          10.5                                      __________________________________________________________________________

                  TABLE 12                                                         ______________________________________                                         Results after 10th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid      Around interface of                                                                          L                                             No.    phase       gas-liquid phases                                                                            value                                         ______________________________________                                         401    0           10            85.6                                          402    0           14            85.6                                          403    0           12            85.6                                          404    0           10            85.5                                          405    0           11            85.5                                          406    0           14            85.5                                          407    0           10            85.5                                          408    0           12            85.6                                          409    0           14            85.5                                          410    0           17            85.5                                          412    0           15            85.6                                          412    0           18            85.6                                          413    0           16            85.5                                          414    0           13            85.4                                          415    0           15            85.5                                          416    0           16            85.5                                          417    0           14            85.5                                          419    0           32            85.5                                          419    0           30            85.5                                          420    0           31            85.5                                          421    0           52            85.3                                          422    0           58            85.4                                          ______________________________________                                    

Production Example 3

Production of Condensation Product No.44

An autoclave was charged with 980 g of methanol, 10 g of p-aminophenol as the aromatic amine compound (A-1) and 8 g of 4-aminodiphenylamine as the aromatic amine compound (A-2), and they were stirred, so that the p-aminophenol and 4-aminodiphenylamine were dissolved in the methanol.

The methanol solution thus obtained was added with 2 g of p-benzoquinone as the quinone compound (B), and the mixture obtained was heated to 30° C., subjected to reaction at 30° C. for 50 hours, and then cooled. Thus, a methanol solution of Condensation Product No.44 was obtained.

Production of Condensation Product Nos.45-54

In each production, the procedure of Production Condensation Product No.44 was repeated, except for using aromatic amine compounds (A-1) and (A-2) and a quinone compound (B) given in Table 13 and a solvent given in Table 14 under conditions given in Table 14 (total concentration, (A-1):(A-2):(B) ratio, reaction temperature and reaction time). Thus, Condensation Product Nos.45 to 54 were obtained.

Production of Condensation Product No.55

An autoclave was charged with 980 g of methanol, 5 g of 4-aminodiphenylamine as the aromatic amine compound (A-2) and 10 g of p-aminobenzoic acid as the aromatic amine compound (A-1), and they were stirred, so that the 4-aminodiphenylamine and p-aminobenzoic acid were dissolved in the methanol.

The methanol solution thus obtained was added with 5 g of 2-hydroxy-1,4-naphthoquinone as the quinone compound (B), and the mixture obtained was heated to 50° C., subjected to reaction at 50° C. for 5 hours, and then cooled. Then, the reaction mixture was added with water in the amount which is five times the amount of the reaction mixture. Subsequently, the pH of the mixture was adjusted to 2 to 3 by the addition of 1% sulfuric acid, so that the condensation product was settled. The sediment thus formed was filtered off, washed with water and dried to give Condensation Product No.55.

Production of Condensation Product Nos.56-65

In each production, the procedure of Production Condensation Product No.55 was repeated, except for using aromatic amine compounds (A-1) and (A-2) and a quinone compound (B) given in Table 13 and a solvent given in Table 14 under conditions given in Table 14 (total concentration, (A-1):(A-2):(B) ratio, reaction temperature and reaction time). Thus, Condensation Product Nos.56 to 65 were obtained.

                                      TABLE 13                                     __________________________________________________________________________     Condensation                                                                   product                                                                               (A) Aromatic amine compound                                                                              (B) Quinone                                   No.    (A-1)        (A-2)        compound                                      __________________________________________________________________________     44     p-Aminophenol                                                                               4-Aminodiphenylamine                                                                        p-Benzoquinone                                45     p-Aminophenol                                                                               2-Aminodiphenylamine                                                                        p-Benzoquinone                                46     m-Aminophenol                                                                               2-Aminodiphenylamine                                                                        p-Benzoquinone                                47     o-Aminophenol                                                                               4,4'-Diaminophenylamine                                                                     o-Benzoquinone                                48     4-Amino-2-aminophenol                                                                       4-Aminodiphenylamine                                                                        p-Toluquinone                                 49     p-Aminophenol                                                                               m-Phenylenediamine                                                                          Hydorxy-p-                                                                     benzoquinone                                  50     p-Aminophenol                                                                               4-Aminodiphenylamine                                                                        Bromo-p-                                                                       benzoquinone                                  51     2-Nitro-4-aminophenol                                                                       4-Aminodiphenylamine                                                                        Duroquinone                                   52     4-Amino-2-aminophenol                                                                       p-Phenylenediamine                                                                          Chloro-p-                                                                      benzoquinone                                  53     p-Aminophenol                                                                               m-Phenylenediamine                                                                          p-Benzoquinone                                54     p-Aminophenol                                                                               2,3-Diaminotoluene                                                                          p-Benzoquinone                                55     p-Aminobenzoic acid                                                                         4-Aminodiphenylamine                                                                        2-Hydroxy-1,4-                                                                 naphthoquinone                                56     m-Aminobenzoic acid                                                                         4-Aminodiphenylamine                                                                        o-Benzoquinone                                57     p-Aminosalicylic acid                                                                       1,8-Diaminonaphtalene                                                                       p-Benzoquinone                                58     3,5-Diaminonbenzoic acid                                                                    2-Aminodiphenylamine                                                                        α-Naphthoquinon                         59     2,4-Diaminonbenzoic acid                                                                    α-Naphthylamine                                                                       Lawson                                        60     2-Amino-5-naphthol-7-                                                                       p-Phenylenediamine                                                                          p-Benzoquinone                                       sulfonic acid                                                           61     1-Amino-8-hydorxy-3,6-                                                                      4-Aminodiphenylamine                                                                        p-Benzoquinone                                       disulfonic acid                                                         62     2-Amino-8-naphthol-6-                                                                       Aniline      2-Hydroxy-1,4-                                       sulfonic acid             naphthoquinone                                63     p-Diaminobenzene-                                                                           4-Aminodiphenylamine                                                                        p-Benzoquinone                                       sulfonic acid                                                           64     2,5-Diaminobenzene-                                                                         1,8-Diaminonaphthalene                                                                      α-Naphthoquinon                                sulfonic acid                                                           65     2,4-Diaminobenzene-                                                                         4-Aminodiphenylamine                                                                        p-Benzoquinone                                       sulfonic acid                                                           __________________________________________________________________________

                                      TABLE 14                                     __________________________________________________________________________                     Total conc.    Reaction                                        Condensation    of (A-1) +     tempera-                                                                            Reaction                                   product                                                                               Solvent  (A-2) + (B)                                                                           (A-1):(A-2):(B)                                                                        ture time                                       No.    (wt. ratio)                                                                             (wt. %)                                                                               (wt. ratio)                                                                            (°C.)                                                                        (Hr)                                       __________________________________________________________________________     44     Methanol 2.0    100:80:20                                                                              30   50                                         45     Methanol 2.0    100:80:20                                                                              25   50                                         46     Methanol 3.0    100:200:50                                                                             50   5                                          47     Methanol 1.0    100:10:10                                                                              80   2                                          48     Methanol 0.5    100:30:50                                                                              130  0.5                                        49     Methanol 0.5    100:30:5                                                                               100  0.5                                        50     Methanol:Water                                                                          1.0    100:100:10                                                                             50   0.5                                               (80:20)                                                                 51     Methanol 1.0    100:100:20                                                                             30   20                                         52     Methanol 2.0    100:50:20                                                                              40   30                                         53     Methanol:Water                                                                          2.0    100:50:20                                                                              50   10                                                (80:20)                                                                 54     Methanol 2.5    100:80:10                                                                              50   5                                          55     Methanol 2.0    100:50:50                                                                              30   50                                         56     Methanol:Water                                                                          1.0    100:100:50                                                                             50   15                                                (80:20)                                                                 57     Methanol:Water                                                                          1.0    100:20:10                                                                              80   5                                                 (80:20)                                                                 58     Methanol:Water                                                                          2.0    100:30:200                                                                             60   5                                                 (80:20)                                                                 59     Methanol:Water                                                                          2.0    100:100:100                                                                            60   10                                                (80:20)                                                                 60     Methanol 2.0    100:33:10                                                                              30   40                                         61     Methanol 1.0    100:20:4                                                                               50   10                                         62     Methanol:Water                                                                          2.0    100:50:15                                                                              50   7                                                 (80:20)                                                                 63     Methanol 2.0    100:50:25                                                                              50   5                                          64     Methanol:Water                                                                          2.0    100:20:500                                                                             30   30                                                (70:30)                                                                 65     Methanol:Water                                                                          2.0    100:50:1000                                                                            50   10                                                (80:20)                                                                 __________________________________________________________________________

Example 5 (Experiment Nos. 501 to 522)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 1,000 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 15 under conditions given in Table 15 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 1. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 50 times. After the 50th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 1.

The results are given in Table 16.

                                      TABLE 15                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation       Concen-                                                  Exp.                                                                              product                                                                               Solvent     tration                                                  No.                                                                               No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                        __________________________________________________________________________     501                                                                               44     Water:Methanol (80:20)                                                                     0.2  NaOH      9.5                                       502                                                                               45     Water:Methanol (80:20)                                                                     0.2  NaOH      9.5                                       503                                                                               46     Water:Methanol (80:20)                                                                     0.1  KOH       9.5                                       504                                                                               47     Water:Methanol (90:10)                                                                     0.05 KOH       11.0                                      505                                                                               48     Water:Methanol (70:30)                                                                     0.3  Na.sub.2 CO.sub.3                                                                        9.0                                       506                                                                               49     Water:Methanol (80:20)                                                                     0.5  LiOH      12.0                                      507                                                                               50     Water:Methanol (80:20)                                                                     0.2  Na.sub.2 SiO.sub.3                                                                       10.0                                      508                                                                               51     Water:Methanol (80:20)                                                                     0.2  NH.sub.4 OH                                                                              10.5                                      509                                                                               52     Water:Methanol (80:20)                                                                     0.2  NaOH      9.0                                       510                                                                               53     Water:Methanol (90:10)                                                                     0.2  NaOH      11.5                                      511                                                                               54     Water:Methanol (80:20)                                                                     0.2  Monoethanolamine                                                                         9.5                                       512                                                                               55     Water:Methanol (80:20)                                                                     0.1  Ethylenediamine                                                                          9.5                                       513                                                                               56     Water:Methanol (70:30)                                                                     0.2  NaOH      11.0                                      514                                                                               57     Water:Methanol (70:30)                                                                     0.2  Triethanolamine                                                                          10.0                                      515                                                                               58     Water:Methanol (90:10)                                                                     0.2  NaOH      9.0                                       516                                                                               59     Water:Methanol (90:10)                                                                     0.2  Ethylenediamine                                                                          9.5                                       517                                                                               69     Water:Methanol (80:20)                                                                     0.2  NaOH      10.0                                      518                                                                               70     Water:Methanol (70:30)                                                                     0.3  Monoethanolamine                                                                         10.0                                      519                                                                               71     Water:Methanol (90:10)                                                                     0.2  LiOH      9.0                                       520                                                                               72     Water:Methanol (90:10)                                                                     0.2  Ethylenediamine                                                                          9.5                                       521                                                                               73     Water:Methanol (70:30)                                                                     0.2  NaOH      9.0                                       522                                                                               74     Water:Methanol (80:20)                                                                     0.2  NaOH      9.0                                       __________________________________________________________________________

                  TABLE 16                                                         ______________________________________                                         Results after 50th polymerization batch                                        Scale amount (g/m.sup.2)   No. of                                              Exp.   Liquid  Around interface of                                                                            fish  L                                         No.    phase   gas-liquid phases                                                                              eyes  value                                     ______________________________________                                         501    0        6              6     72.6                                      502    0        6              7     72.7                                      503    0        7              6     72.7                                      504    0       18              10    72.8                                      505    0        7              7     72.6                                      506    0        7              7     72.8                                      507    0        8              8     72.7                                      508    0        8              7     72.7                                      509    0        7              7     72.6                                      510    0        7              6     72.6                                      511    0        7              7     72.7                                      512    0       15              11    71.4                                      513    0       15              10    71.4                                      514    0       13              10    71.4                                      515    0       12              8     71.7                                      516    0       14              9     71.8                                      517    0       12              9     71.4                                      518    0       16              11    71.4                                      519    0       16              10    71.4                                      520    0       15              10    71.3                                      521    0       11              8     71.8                                      522    0       10              8     71.8                                      ______________________________________                                    

Example 6 (Experiment Nos. 601 to 622)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 17 under conditions given in Table 17 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 2. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 15 times. After the 15th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 2.

The results are given in Table 18.

                                      TABLE 17                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation       Concen-                                                  Exp.                                                                              production                                                                            Solvent     tration                                                  No.                                                                               No.    (wt. ratio) (wt. %)                                                                             Alkaline compound                                                                        pH                                        __________________________________________________________________________     601                                                                               51     Water:Methanol (80:20)                                                                     0.2  NaOH      10.5                                      602                                                                               54     Water:Methanol (80:20)                                                                     0.2  NaOH      10.5                                      603                                                                               55     Water:Methanol (80:20)                                                                     0.3  KOH       10.0                                      604                                                                               56     Water:Methanol (70:30)                                                                     0.3  NH.sub.4 OH                                                                              9.0                                       605                                                                               57     Water:Methanol (80:20)                                                                     0.3  Monoethanolamine                                                                         9.5                                       606                                                                               58     Water:Methanol (80:20)                                                                     0.3  NaOH      9.5                                       607                                                                               59     Water:Methanol (80:20)                                                                     0.3  NaOH      11.0                                      608                                                                               60     Water:Methanol (80:20)                                                                     0.3  NaOH      12.0                                      609                                                                               61     Water:Methanol (90:10)                                                                     0.3  NaOH      12.5                                      610                                                                               62     Water:Methanol (90:10)                                                                     0.3  NaOH      11.0                                      611                                                                               63     Water:Methanol (80:20)                                                                     0.3  NaOH      10.5                                      612                                                                               65     Water:Methanol (80:20)                                                                     0.3  Triethanolamine                                                                          10.0                                      613                                                                               64     Water:Methanol (70:30)                                                                     0.2  NaOH      11.0                                      614                                                                               66     Water:Methanol (70:30)                                                                     0.2  Ethylenediamine                                                                          11.0                                      615                                                                               67     Water:Methanol (90:10)                                                                     0.3  NaOH      10.5                                      616                                                                               68     Water:Methanol (90:10)                                                                     0.3  NaOH      10.0                                      617                                                                               69     Water:Methanol (70:30)                                                                     0.3  Ethylenediamine                                                                          10.0                                      618                                                                               70     Water:Methanol (80:20)                                                                     0.2  Ethylenediamine                                                                          11.0                                      619                                                                               71     Water:Methanol (90:10)                                                                     0.2  Na.sub.2 CO.sub.3                                                                        12.0                                      620                                                                               72     Water:Methanol (90:10)                                                                     0.2  NH.sub.4 OH                                                                              12.0                                      621                                                                               73     Water:Methanol (90:10)                                                                     0.2  NaOH      10.0                                      622                                                                               74     Water:Methanol (90:10)                                                                     0.3  NaOH      10.0                                      __________________________________________________________________________

                  TABLE 18                                                         ______________________________________                                                Results after 15th polymeirzation batch                                        Scale amount (g/m.sup.2)                                                Exp.   Liquid      Around interface of                                                                          L                                             No.    phase       gas-liquid phases                                                                            value                                         ______________________________________                                         601    0            7            85.6                                          602    0           10            85.6                                          603    0           16            85.6                                          604    0           11            85.6                                          605    0           12            85.6                                          606    0            9            85.5                                          607    0            8            85.6                                          608    0           11            85.6                                          609    0           13            85.5                                          610    0           10            85.6                                          611    0            9            85.6                                          612    0           12            84.7                                          613    0           16            84.7                                          614    0           17            84.7                                          615    0           16            84.8                                          616    0           13            84.8                                          617    0           17            84.7                                          618    0           20            84.8                                          619    0           21            84.7                                          620    0           17            84.7                                          621    0           15            84.9                                          622    0           12            84.8                                          ______________________________________                                    

Production Example 4

Production of Condensation Product No.66

An autoclave was charged with 882 g of methanol, 4 g of 4-aminodiphenylamine as the aromatic amine compound (A-2) and 10 g of 4-aminosalycilic acid as the aromatic amine compound (A-1), and they were stirred, so that the 4-aminodiphenylamine and the 4-aminosalycilic acid were dissolved in the methanol.

The methanol solution thus obtained was added with 2 g of 1,4-naphthoquinone as the quinone compound (B), and the mixture obtained was heated to 40° C., subjected to reaction at 40° C. for 10 hours, and then added with 4 g of sodium hydrosulfite as the reaction stopper (C) dissolved in 98 g of water. The condensation conversion of the aromatic amine compounds and the quinone compound at the time when the reaction stopper (C) began to be added, was measured in accordance with the method below and found to be 97% by weight.

The solution to which the reaction stopper was added as mentioned above was stirred for another 10 hours and then cooled to give the solution of Condensation Product No.66.

--Measurement of condensation conversion

The unreacted aromatic amine compound (i.e., 4-aminodiphenylamine and 4-aminosalycilic acid in the production of Condensation Product No.66) and quinone compound (i.e., 1,4-naphthoquinone) in a reaction mixture is determined by liquid chromatography.

The condensation conversion is calculated by the equation:

    Condensation conversion (% by weight)=[(a-b)/a)]×100

wherein a stands for the total amount of the aromatic amine compounds and quinone compounds charged and b stands for the amount of the unreacted aromatic amine compounds and quinone compounds determined as above.

Production of Condensation Product Nos.67-82

In each production, the procedure of Production Condensation Product No.66 was repeated, except for using aromatic amine compounds (A-1) and (A-2) and a quinone compound (B) given in Table 19 and a solvent given in Table 20 under conditions given in Table 20 (total concentration, (A-1):(A-2):(B):(C) ratio, reaction temperature, elapsed time from the start of the condensation of the components (A) and (B) until the component began to be added (hereinafter referred to "elapsed time till addition of (C)"), condensation conversion of the components (A) and (B) at the time when the component (C) began to be added, stirring time after the addition of the components (C), and entire reaction time from the start of the condensation of the components (A) and (B) until the stirring after the addition of the component (C) was stopped (hereinafter referred to "entire reaction time")).

Production of Condensation Product Nos.83-111

In each production, the procedure of Production Condensation Product No.66 was repeated, except for using aromatic amine compounds (A-1) and (A-2), a quinone compound (B) and a reaction stopper (C) given in Table 21, 23 and 25 and a solvent given in Table 22, 24 and 26 under conditions given in Table 22, 24 and 26 (total concentration, (A-1):(A-2):(B):(C) ratio, reaction temperature, elapsed time till addition of (C), condensation conversion of the components (A) and (B) when the component (C) began to be added, stirring time after the addition of the components (C), and entire reaction time).

It is noted that the condensation products of Nos. 92-95 are those in which an aromatic amine compound (A-1) was only used as the component (A).

                                      TABLE 19                                     __________________________________________________________________________     Conden-                                                                        sation                   (B)      (C)                                          product                                                                             (A) Aromatic amine compound                                                                        Quinone  Reaction                                     No.  (A-1)   (A-2)       compound stopper                                      __________________________________________________________________________     66   4-Amino-                                                                               4-Aminodiphenylamine                                                                       1,4-     Sodium hydro-                                     salicylic acid      Naphthoquinone                                                                          sulfite                                      67   2,3-Diamino-                                                                           2-Aminodiphenylamine                                                                       2-Hydroxy-1,4-                                                                          Sodium sulfide                                    benzoic acid                                                              68   2,6-Diamino-                                                                           4,4'-Diamino-                                                                              p-Benzoquinone                                                                          Potassium sulfite                                 terephthalic                                                                           diphenylamine                                                          acid                                                                      69   4-Hydroxyanth-                                                                         4-Aminodiphenylamine                                                                       p-Toluquinone                                                                           Sodium bisulfite                                  ranilic acid                                                              70   α-Naphthyl-                                                                      α-naphthylamine                                                                      p-Benzoquinone                                                                          Sodium hydro-                                     amine-β-car-            sulfite                                           boxylic acid                                                              71   3,5-Diamino-                                                                           2-Nitro-4-  p-Benzoquinone                                                                          Rongalit                                          benzoic acid                                                                           aminophenol                                                       72   4-Amino-                                                                               1,8-Diamino-                                                                               p-Benzoquinone                                                                          Sodium sulfide                                    salicylic acid                                                                         naphthalene                                                       73   4-Aminoiso-                                                                            4-Aminodiphenylamine                                                                       α- Sodium hydro-                                     phthalic acid       Naphthoquinone                                                                          sulfite                                      74   p-Amino-                                                                               p-Phenylenediamine                                                                         p-Benzoquinone                                                                          Sodium hydro-                                     benzenesul-                  sulfite                                           fonic acid                                                                75   H-acid  5-Nitro-2-  p-Toluquinone                                                                           Phosphorus                                                aminophenol          trichloride                                  76   J-acid  Aniline     p-Benzoquinone                                                                          Sodium hydro-                                                                  sulfite                                      77   p-Amino-                                                                               m-Phenylenediamine                                                                         p-Benzoquinone                                                                          Potassium sulfite                                 benzenesul-                                                                    fonic acid                                                                78   H-acid  α-Naphthylamine                                                                      Duroquinone                                                                             Hydrazine                                    79   J-acid  2,3-Diamino-                                                                               p-Benzoquinone                                                                          Rongalit                                                  naphthalene                                                       80   o-Amino-                                                                               2-Aminodiphenylamine                                                                       Lawson   Rongalit                                          benzenesul-                                                                    fonic acid                                                                81   2,4-Amino-                                                                             1,8-Diamino-                                                                               α- Sodium hydro-                                     benzenesul-                                                                            naphthalene Naphthoquinone                                                                          sulfite                                           fonic acid                                                                82   2,5-Amino-                                                                             p-Phenylenediamine                                                                         p-Benzoquinone                                                                          Sodium hydro-                                     benzenesul-                  sulfite                                           fonic acid                                                                __________________________________________________________________________

                                      TABLE 20                                     __________________________________________________________________________                   Total                Elapsed                                                                             Conden-                                Conden-       conc. of        Reaction                                                                            time till                                                                           sation                                                                              Entire                            sation        (A-1) + (A-1):(A-2):                                                                           temper-                                                                             addition                                                                            conver-                                                                             reaction                                                                            Stirring                     product                                                                             Solvent  (A-2) + (B) +                                                                          (B):(C) ature                                                                               of (C)                                                                              sion time time                         No.  (wt. ratio)                                                                             (C) (wt. %)                                                                            (wt. ratio)                                                                            (°C.)                                                                        (Hr) (%)  (Hr) (Hr)                         __________________________________________________________________________     66   Methanol:Water                                                                          2.0     250:100:50:100                                                                         40   10   97   20   10                                (90:10)                                                                   67   Methanol:Water                                                                          1.0     500:100:100:200                                                                        100  10   97   15   5                                 (90:10)                                                                   68   Methanol:Water                                                                          1.0     500:100:200:200                                                                        100   8   85   10   2                                 (90:10)                                                                   69   Methanol:Water                                                                          0.5     500:100:50:100                                                                         150   8   95   10   2                                 (90:10)                                                                   70   Methanol:Water                                                                          2.0     200:100:50:50                                                                          50   10   94   15   5                                 (90:10)                                                                   71   Methanol:Water                                                                          3.0     100:50:150:30                                                                          60   10   95   15   5                                 (60:40)                                                                   72   Methanol:Water                                                                          3.0     100:30:200:50                                                                          50   10   90   15   5                                 (70:30)                                                                   73   Methanol:Water                                                                          3.0     100:30:200:50                                                                          50   10   87   15   5                                 (70:30)                                                                   74   Methanol:Water                                                                          2.0     200:100:100:100                                                                        50   10   87   20   10                                (80:20)                                                                   75   Methanol:Water                                                                          1.0     100:100:50:50                                                                          50   10   88   15   5                                 (80:20)                                                                   76   Methanol:Water                                                                          5.0     100:50:30:50                                                                           100   8   82   10   2                                 (80:20)                                                                   77   Methanol:Water                                                                          2.0     200:100:50:100                                                                         150   8   97   20   12                                (80:20)                                                                   78   Methanol:Water                                                                          2.0     150:100:50:30                                                                          50   30   86   40   10                                (50:50)                                                                   79   Methanol:Water                                                                          2.0     50:100:50:50                                                                           30   10   96   20   10                                (70:30)                                                                   80   Methanol:Water                                                                          3.0     100:50:200:50                                                                          70   10   96   20   10                                (60:40)                                                                   81   Methanol:Water                                                                          3.0     100:50:100:30                                                                          50   10   92   20   10                                (60:40)                                                                   82   Methanol:Water                                                                          3.0     100:20:100:30                                                                          50   10   95   20   10                                (60:40)                                                                   __________________________________________________________________________

                                      TABLE 21                                     __________________________________________________________________________     Conden-                                                                        sation                   (B)      (C)                                          product                                                                             (A) Aromatic amine compound                                                                        Quinone  Reaction                                     No.  (A-1)   (A-2)       compound stopper                                      __________________________________________________________________________     83   p-Aminophenol                                                                          4-Aminodiphenyl-                                                                           p-Benzoquinone                                                                          Pyrogallol                                                amine                                                             84   p-Aminophenol                                                                          1,8-Diaminonaphtha-                                                                        o-Benzoquinone                                                                          Phenol                                                    lene                                                              85   4-Amino-2-                                                                             m-Phenylenediamine                                                                         p-Benzoquinone                                                                          Catechol                                          aminophenol                                                               86   2-Nitro-4-                                                                             2,3-Diaminotoluene                                                                         α- β-Naphthol                                   aminophenol         Naphthoquinone                                        87   m-Aminophenol                                                                          p-Phenylenediamine                                                                         α- Resorcinol                                                            Naphthoquinone                                        88   p-Amino-                                                                               4-Aminodiphenylamine                                                                       p-Benzoquinone                                                                          Pyrogallol                                        salicylic acid                                                            89   p-Aminophenol                                                                          1,8-Diaminonaphtha-                                                                        Duroquinone                                                                             Hydroxybenzoic                                            lene                 acid                                         90   p-Aminobenzoic                                                                         4-Aminodiphenyl-                                                                           α- Hydroquinone                                      acid    amine       Naphthoquinone                                        91   p-Aminophenol                                                                          4-4'-Diamino-                                                                              Juglone  α-Naphthol                                          diphenylamine                                                     92   p-Amino-                                                                               --          Lawson   2,7-Dihydroxy-                                    salicylic acid               naphthalene                                  93   m-Aminophenol                                                                          --          p-Benzoquinone                                                                          Pyrogallol                                   94   p-Aminophenol                                                                          --          α- Hydroxyhydro-                                                         Naphthoquinone                                                                          quinone                                      95   o-Aminophenol                                                                          --          o-Benzoquinone                                                                          Resorcinol                                   __________________________________________________________________________

                                      TABLE 22                                     __________________________________________________________________________                   Total                Elapsed                                                                             Conden-                                Conden-       conc. of        Reaction                                                                            time till                                                                           sation                                                                              Entire                            sation        (A-1) + (A-1):(A-2):                                                                           temper-                                                                             addition                                                                            conver-                                                                             reaction                                                                            Stirring                     product                                                                             Solvent  (A-2) + (B) +                                                                          (B):(C) ature                                                                               of (C)                                                                              sion time time                         No.  (wt. ratio)                                                                             (C) (wt. %)                                                                            (wt. ratio)                                                                            (°C.)                                                                        (Hr) (%)  (Hr) (Hr)                         __________________________________________________________________________     83   Methanol 2.0     100:50:20:30                                                                           40   10   92   50   40                           84   Methanol 2.0     100:50:20:100                                                                          50   5    90   50   45                           85   Methanol:Water                                                                          2.5     100:100:10:100                                                                         30   10   93   50   40                                (80:20)                                                                   86   Methanol 1.5     100:200:20:200                                                                         60   20   78   50   30                           87   Methanol 1.5     100:50:50:50                                                                           100  10   89   50   40                           88   Methanol 1.5     100:100:50:50                                                                          80   5    79   50   45                           89   Methanol 1.0     100:150:10:100                                                                         30   3    82   50   47                           90   Methanol 1.0     100:100:10:100                                                                         30   5    78   50   45                           91   Methanol 1.0     100:100:20:50                                                                          30   10   80   50   40                           92   Methanol 1.5     100:--:20:50                                                                           60   10   87   50   40                           93   Methanol 2.0     100:--:20:50                                                                           60   5    95   50   45                           94   Methanol 1.0     100:--:50:50                                                                           50   5    94   50   45                           95   Methanol 2.0     100:--:20:100                                                                          40   5    90   50   45                           __________________________________________________________________________

                                      TABLE 23                                     __________________________________________________________________________     Conden-                                                                        sation                  (B)      (C)                                           product                                                                             (A) Aromatic amine compound                                                                       Quinone  Reaction                                      No.  (A-1)    (A-2)     compound stopper                                       __________________________________________________________________________     96   p-Aminophenol                                                                           4-Aminodiphenyl-                                                                         p-Benzoquinone                                                                          Sodium hydro-                                               amine              sulfite                                       97   4-Amino-2-                                                                              m-Phenylenediamine                                                                       α- Sodium tiosulfate                                  aminophenol        Naphthoquinone                                         98   m-Aminophenol                                                                           2-Aminodiphenyl-                                                                         p-Benzoquinone                                                                          Sodium sulfide                                              amine                                                            99   1-Amino-5-                                                                              p-Phenylenediamine                                                                       p-Benzoquinone                                                                          Sodium tiosulfate                                  hydroxynaphtha-                                                                lene                                                                      100  m-Aminophenol                                                                           2-Aminodiphenyl-                                                                         Duroquinone                                                                             Rongalit                                                    amine                                                            101  2,4-Diamino-                                                                            4-Aminodiphenyl-                                                                         α- Rongalit                                           benzenesulfonic                                                                         amine     Naphthoquinone                                              acid                                                                      102  3,5-Diamino-                                                                            1,8-Diamino-                                                                             p-Benzoquinone                                                                          Ammonium sulfide                                   benzoic acid                                                                            naphthalene                                                      __________________________________________________________________________

                                      TABLE 24                                     __________________________________________________________________________                   Total                Elapsed                                                                             Conden-                                Conden-       conc. of        Reaction                                                                            time till                                                                           sation                                                                              Entire                            sation        (A-1) + (A-1):(A-2):                                                                           temper-                                                                             addition                                                                            conver-                                                                             reaction                                                                            Stirring                     product                                                                             Solvent  (A-2) + (B) +                                                                          (B):(C) ature                                                                               of (C)                                                                              sion time time                         No.  (wt. ratio)                                                                             (C) (wt. %)                                                                            (wt. ratio)                                                                            (°C.)                                                                        (Hr) (%)  (Hr) (Hr)                         __________________________________________________________________________     96   Methanol:Water                                                                          2.0     100:50:30:20                                                                           30    8   78   30   22                                (90:10)                                                                   97   Methanol:Water                                                                          2.0     100:100:50:100                                                                         50    5   83   30   25                                (90:10)                                                                   98   Methanol/Water                                                                          1.0     100:30:30:10                                                                           30   20   84   30   10                                (90:10)                                                                   99   Methanol:Water                                                                          1.0     100:20:10:30                                                                           50   25   96   30    5                                (90:10)                                                                   100  Methanol:Water                                                                          2.0     100:100:100:100                                                                        25    8   75   30   22                                (80:20)                                                                   101  Methanol:Water                                                                          3.0     100:50:30:200                                                                          50   10   87   15    5                                (60:40)                                                                   102  Methanol:Water                                                                          3.0     100:50:50:100                                                                          50   10   89   15    5                                (60:40)                                                                   __________________________________________________________________________

                                      TABLE 25                                     __________________________________________________________________________     Conden-                          (C)                                           sation                  (B)      Natural aromatic                              product                                                                             (A) Aromatic amine compound                                                                       Quinone  hydroxyl-containing                           No.  (A-1)    (A-2)     compound organic compound                              __________________________________________________________________________     103  p-Aminophenol                                                                           4-Aminodiphenyl-                                                                         p-Benzoquinone                                                                          Mimosa tannin                                               amine                                                            104  m-Aminophenol                                                                           1,8-Diamino-                                                                             1,4-     Lignin                                                      naphthalene                                                                              Naphthoquinone                                         105  p-Aminobenzoic                                                                          o-Phenylenediamine                                                                       Duroquinone                                                                             Tara tanin                                         acid                                                                      106  p-Amino- 1,8-Diamino-                                                                             p-Benzoquinone                                                                          Mangrove tannin                                    salicylic acid                                                                          naphthalene                                                      107  p-Aminosulfonic                                                                         4-Aminodiphenyl-                                                                         1,4-     Lignin                                             acid     amine     Naphthoquinone                                         108  p-Aminophenol                                                                           m-Phenylenediamine                                                                       2-Hydroxy-1,4-                                                                          Mimosa tannin                                                         naphthoquinone                                         109  p-Aminophenol                                                                           1,8-Diamino-                                                                             p-Benzoquinone                                                                          Tannin of persimmon                                         naphthalene                                                      110  3,5-Diaminoben-                                                                         4-Aminodiphenyl-                                                                         α- Chinese gallotannin                                zoic acid                                                                               amine     Naphthoquinone                                         111  2,5-Diaminoben-                                                                         m-Phenylenediamine                                                                       p-Benzoquinone                                                                          Myrobalan tannin                                   zenesulfonic                                                                   acid                                                                      __________________________________________________________________________

                                      TABLE 26                                     __________________________________________________________________________                   Total                Elapsed                                                                             Conden-                                Conden-       conc. of        Reaction                                                                            time till                                                                           sation                                                                              Entire                            sation        (A-1) + (A-1):(A-2):                                                                           temper-                                                                             addition                                                                            conver-                                                                             reaction                                                                            Stirring                     product                                                                             Solvent  (A-2) + (B) +                                                                          (B):(C) ature                                                                               of (C)                                                                              sion time time                         No.  (wt. ratio)                                                                             (C) (wt. %)                                                                            (wt. ratio)                                                                            (°C.)                                                                        (Hr) (%)  (Hr) (Hr)                         __________________________________________________________________________     103  Methanol:Water                                                                          2.5     100:20:30:10                                                                           40   20   93   50   30                                (70:30)                                                                   104  Methanol:Water                                                                          1.0     100 10:50:200                                                                          20   20   94   50   30                                (80:20)                                                                   105  Methanol:Water                                                                          2.0     100:50:10:100                                                                          50   30   92   50   20                                (90:10)                                                                   106  Methanol:Water                                                                          1.5     100:50:10:50                                                                           50   45   98   50    5                                (90:10)                                                                   107  Methanol:Water                                                                          1.5     100:10:50:50                                                                           50   10   95   50   40                                (90:10)                                                                   108  Methanol:Water                                                                          2.0     100:20:50:50                                                                           40   10   91   50   40                                (70:30)                                                                   109  Methanol:Water                                                                          2.0     100:20:50:50                                                                           40   10   93   50   40                                (70:30)                                                                   110  Methanol:Water                                                                          3.0     100:20:200:100                                                                         40   10   88   15    5                                (70:30)                                                                   111  Methanol:Water                                                                          3.0     100:40:200:100                                                                         40   15   94   20    5                                (70:30)                                                                   __________________________________________________________________________

Example 7 (Experiment Nos. 701 to 746)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 1,000 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 27 and 28 under conditions given in Table 27 and 28 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 1. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 100 times. After the 100th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 1.

The results are given in Table 29 and 30.

                                      TABLE 27                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation                                                                Exp.                                                                              product                                                                               Solvent     Concentration                                            No.                                                                               No.    (wt. ratio) (wt. %) Alkaline compound                                                                        pH                                     __________________________________________________________________________     701                                                                               66     Water:Methanol (90:10)                                                                     0.3     NaOH      9.0                                    702                                                                               67     Water:Methanol (80:20)                                                                     0.5     NaOH      9.5                                    703                                                                               68     Water:Methanol (80:20)                                                                     0.1     KOH       10.0                                   704                                                                               69     Water:Methanol (80:20)                                                                     0.05    KOH       10.0                                   705                                                                               70     Water:Methanol (90:10)                                                                     0.2     NaOH      9.0                                    706                                                                               71     Water:Methanol (80:20)                                                                     0.3     NaOH      9.0                                    707                                                                               72     Water:Methanol (80:20)                                                                     0.3     Ethylenediamine                                                                          9.5                                    708                                                                               73     Water:Methanol (80:20)                                                                     0.3     KOH       9.0                                    709                                                                               74     Water:Methanol (90:10)                                                                     0.3     NaOH      8.5                                    710                                                                               75     Water:Methanol (90:10)                                                                     0.3     NaOH      9.0                                    711                                                                               76     Water:Methanol (80:20)                                                                     0.5     Ethylenediamine                                                                          9.0                                    712                                                                               77     Water:Methanol (80:20)                                                                     0.2     Triethanolamine                                                                          10.0                                   713                                                                               78     Water:Methanol (70:30)                                                                     0.2     NaOH      11.0                                   714                                                                               79     Water:Methanol (60:40)                                                                     0.2     NaOH      12.0                                   715                                                                               80     Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    716                                                                               81     Water:Methanol (80:20)                                                                     0.3     KOH       9.5                                    717                                                                               82     Water:Methanol (80:20)                                                                     0.3     Ethylenediamine                                                                          9.5                                    718                                                                               83     Water:Methanol (70:30)                                                                     0.3     Triethanolamine                                                                          8.5                                    719                                                                               84     Water:Methanol (80:20)                                                                     0.3     NaOH      9.0                                    720                                                                               85     Water:Methanol (80:20)                                                                     0.3     Ethylenediamine                                                                          9.5                                    721                                                                               86     Water:Methanol (80:20)                                                                     0.2     KOH       10.0                                   722                                                                               87     Water:Methanol (80:20)                                                                     0.1     KOH       10.0                                   723                                                                               88     Water:Methanol (80:20)                                                                     0.3     KOH       10.0                                   __________________________________________________________________________

                                      TABLE 28                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation                                                                Exp.                                                                              product                                                                               Solvent     Concentration                                            No.                                                                               No.    (wt. ratio) (wt. %) Alkaline compound                                                                        pH                                     __________________________________________________________________________     724                                                                                89    Water:Methanol (70:30)                                                                     0.3     Ethylenediamine                                                                          11.0                                   725                                                                                90    Water:Methanol (90:10)                                                                     0.3     NaOH      11.0                                   726                                                                                91    Water:Methanol (60:40)                                                                     0.3     NaOH      11.5                                   727                                                                                92    Water:Methanol (50:50)                                                                     0.3     NaOH      12.0                                   728                                                                                93    Water:Methanol (70:30)                                                                     0.2     NaOH      12.0                                   729                                                                                94    Water:Methanol (70:30)                                                                     0.2     Triethanolamine                                                                          9.0                                    730                                                                                95    Water:Methanol (70:30)                                                                     0.3     Triethanolamine                                                                          9.0                                    731                                                                                96    Water:Methanol (80:20)                                                                     0.2     Ethylenediamine                                                                          10.0                                   732                                                                                97    Water:Methanol (80:20)                                                                     0.2     Ethylenediamine                                                                          10.0                                   733                                                                                98    Water:Methanol (70:30)                                                                     0.3     Ethylenediamine                                                                          9.0                                    734                                                                                99    Water:Methanol (70:30)                                                                     0.2     NaOH      9.0                                    735                                                                               100    Water:Methanol (80:20)                                                                     0.2     NaOH      10.0                                   736                                                                               101    Water:Methanol (90:10)                                                                     0.3     NaOH      9.0                                    737                                                                               102    Water:Methanol (90:10)                                                                     0.3     Ethylenediamine                                                                          9.5                                    738                                                                               103    Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    739                                                                               104    Water:Methanol (80:20)                                                                     0.3     NaOH      11.5                                   740                                                                               105    Water:Methanol (90:10)                                                                     0.2     Triethanolamine                                                                          10.0                                   741                                                                               106    Water:Methanol (80:20)                                                                     0.2     Ethylenediamine                                                                          9.0                                    742                                                                               107    Water:Methanol (70:30)                                                                     0.2     Monoethanolamine                                                                         8.0                                    743                                                                               108    Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    744                                                                               109    Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    745                                                                               110    Water:Methanol (90:10)                                                                     0.3     NaOH      10.0                                   746                                                                               111    Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    __________________________________________________________________________

                  TABLE 29                                                         ______________________________________                                         Results after 100th polymerization batch                                       Scale amount (g/m.sup.2)                                                                              No. of                                                  Exp.   Liquid  Around interface of                                                                            fish  L                                         No.    phase   gas-liquid phases                                                                              eyes  value                                     ______________________________________                                         701    0       21              7     72.7                                      702    0       25              8     72.7                                      703    0       24              7     72.7                                      704    1       32              9     72.6                                      705    0       28              8     72.6                                      706    0       17              7     72.7                                      707    0       20              8     72.7                                      708    0       16              7     72.7                                      709    0       21              7     72.6                                      170    0       26              8     72.7                                      711    0       26              7     72.5                                      712    0       27              8     72.7                                      713    0       25              8     72.7                                      714    0       20              7     72.7                                      715    0       22              8     72.7                                      716    0       21              8     72.7                                      717    0       18              8     72.7                                      718    0       24              7     72.7                                      719    0       26              8     72.6                                      720    0       24              7     72.6                                      721    0       23              7     72.5                                      722    0       28              8     72.5                                      723    0       25              8     72.7                                      ______________________________________                                    

                  TABLE 30                                                         ______________________________________                                         Results after 100th polymerization batch                                       Scale amount (g/m.sup.2)                                                                              No. of                                                  Exp.   Liquid  Around interface of                                                                            fish  L                                         No.    phase   gas-liquid phases                                                                              eyes  value                                     ______________________________________                                         724    0       23              7     72.6                                      725    0       21              7     72.6                                      726    0       27              8     72.5                                      727    0       62              24    72.5                                      728    0       73              24    72.5                                      729    0       81              26    72.5                                      730    0       75              25    72.5                                      731    0       20              7     72.7                                      732    0       22              8     72.5                                      733    0       20              7     72.5                                      734    0       21              7     72.6                                      735    0       28              8     72.5                                      736    0       17              7     72.6                                      737    0       20              8     72.7                                      738    0       18              7     72.7                                      739    0       25              8     72.6                                      740    0       27              9     72.6                                      741    0       20              7     72.6                                      742    0       26              8     72.6                                      743    0       30              9     72.5                                      744    0       28              9     72.5                                      745    0       16              7     72.6                                      746    0       18              8     72.6                                      ______________________________________                                    

Example 8 (Experiment Nos. 801 to 844)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product, a solvent and an alkaline compound given in Table 31 and 32 under conditions given in Table 31 and 32 (solvent composition, concentration and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 2. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 50 times. After the 50th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 2.

The results are given in Table 33 and 34.

                                      TABLE 31                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation                                                                Exp.                                                                              product                                                                               Solvent     Concentration                                            No.                                                                               No.    (wt. ratio) (wt. %) Alkaline compound                                                                        pH                                     __________________________________________________________________________     801                                                                               66     Water:Methanol (80:20)                                                                     0.3     NaOH      9.0                                    802                                                                               67     Water:Methanol (70:30)                                                                     0.2     NaOH      9.5                                    803                                                                               68     Water:Methanol (60:40)                                                                     0.2     NaOH      9.5                                    804                                                                               69     Water:Methanol (50:50)                                                                     0.2     NaOH      10.0                                   805                                                                               70     Water:Methanol (80:20)                                                                     0.3     NaOH      10.0                                   806                                                                               71     Water:Methanol (90:10)                                                                     0.3     NaOH      9.5                                    807                                                                               72     Water:Methanol (90:10)                                                                     0.3     NaOH      9.5                                    808                                                                               73     Water:Methanol (80:20)                                                                     0.3     NaOH      10.0                                   809                                                                               74     Water:Methanol (70:30)                                                                     0.3     NaOH      9.0                                    810                                                                               75     Water:Methanol (80:20)                                                                     0.3     NaOH      9.0                                    811                                                                               76     Water:Methanol (80:20)                                                                     0.2     Ethylenediamine                                                                          10.5                                   812                                                                               77     Water:Methanol (80:20)                                                                     0.2     Triethanolamine                                                                          10.5                                   813                                                                               78     Water:Methanol (90:10)                                                                     0.3     NaOH      10.5                                   814                                                                               79     Water:Methanol (90:10)                                                                     0.3     NaOH      11.0                                   815                                                                               80     Water:Methanol (90:10)                                                                     0.3     NaOH      9.5                                    816                                                                               81     Water:Methanol (90:10)                                                                     0.3     NaOH      11.0                                   817                                                                               82     Water:Methanol (80:20)                                                                     0.3     NaOH      11.0                                   818                                                                               83     Water:Methanol (70:30)                                                                     0.2     Triethanolamine                                                                          10.0                                   819                                                                               84     Water:Methanol (70:30)                                                                     0.2     NaOH      11.5                                   820                                                                               85     Water:Methanol (80:20)                                                                     0.3     KOH       11.0                                   821                                                                               86     Water:Methanol (80:20)                                                                     0.3     NaOH      8.5                                    822                                                                               87     Water:Methanol (50:50)                                                                     0.3     Diethanolamine                                                                           8.0                                    __________________________________________________________________________

                                      TABLE 32                                     __________________________________________________________________________     Polymer scale preventive agent                                                    Condensation                                                                Exp.                                                                              product                                                                               Solvent     Concentration                                            No.                                                                               No.    (wt. ratio) (wt. %) Alkaline compound                                                                        pH                                     __________________________________________________________________________     823                                                                                88    Water:Methanol (30:70)                                                                     0.5     Diethanolamine                                                                           12.0                                   824                                                                                89    Water:Methanol (50:50)                                                                     0.2     Diethanolamine                                                                           8.5                                    825                                                                                90    Water:Methanol (80:20)                                                                     0.1     Ethylenediamine                                                                          10.0                                   826                                                                                92    Water:Methanol (80:20)                                                                     0.2     KOH       10.0                                   827                                                                                93    Water:Methanol (80:20)                                                                     0.2     Triethanolamine                                                                          11.0                                   828                                                                                94    Water:Methanol (70:30)                                                                     0.2     Ethylenediamine                                                                          11.0                                   829                                                                                95    Water:Methanol (70:30)                                                                     0.2     NaOH      9.5                                    830                                                                                96    Water:Methanol (80:20)                                                                     0.3     NaOH      9.5                                    831                                                                                97    Water:Methanol (80:20)                                                                     0.3     KOH       9.5                                    832                                                                                98    Water:Methanol (70:30)                                                                     0.2     NaOH      12.0                                   833                                                                                99    Water:Methanol (70:30)                                                                     0.2     Monoethanolamine                                                                         12.0                                   834                                                                               101    Water:Methanol (80:20)                                                                     0.3     NaOH      11.0                                   835                                                                               102    Water:Methanol (80:20)                                                                     0.3     NaOH      10.5                                   836                                                                               103    Water:Methanol (80:20)                                                                     0.3     NaOH      10.0                                   837                                                                               104    Water:Methanol (70:30)                                                                     0.2     NaOH      9.0                                    838                                                                               105    Water:Methanol (70:30)                                                                     0.2     NaOH      8.5                                    839                                                                               106    Water:Methanol (90:10)                                                                     0.3     Ethylenediamine                                                                          10.0                                   840                                                                               107    Water:Methanol (90:10)                                                                     0.3     Ethylenediamine                                                                          11.0                                   841                                                                               108    Water:Methanol (80:20)                                                                     0.3     NaOH      10.5                                   842                                                                               109    Water:Methanol (80:20)                                                                     0.3     NaOH      10.0                                   843                                                                               110    Water:Methanol (90:10)                                                                     0.3     NaOH      9.5                                    844                                                                               111    Water:Methanol (90:10)                                                                     0.3     NaOH      10.0                                   __________________________________________________________________________

                  TABLE 33                                                         ______________________________________                                                Results after 50th polymeirzation batch                                        Scale amount (g/m.sup.2)                                                Exp.   Liquid      Around interface of                                                                          L                                             No.    phase       gas-liquid phases                                                                            value                                         ______________________________________                                         801    0           27            85.6                                          802    0           30            85.6                                          803    0           35            85.6                                          804    0           31            85.5                                          805    0           31            85.6                                          806    0           24            85.6                                          807    0           27            85.6                                          808    0           20            85.6                                          809    0           26            85.6                                          810    0           29            85.6                                          811    0           25            85.6                                          812    0           27            85.6                                          813    0           26            85.6                                          814    0           28            85.6                                          815    0           26            85.6                                          816    0           24            85.6                                          817    0           21            85.6                                          818    0           21            85.6                                          819    1           32            85.6                                          820    2           40            85.6                                          821    3           48            85.7                                          822    1           28            85.6                                          ______________________________________                                    

                  TABLE 34                                                         ______________________________________                                                Results after 50th polymeirzation batch                                        Scale amount (g/m.sup.2)                                                Exp.   Liquid      Around interface of                                                                          L                                             No.    phase       gas-liquid phases                                                                            value                                         ______________________________________                                         823    0           22            85.2                                          824    0           25            85.7                                          825    3           43            85.6                                          826    8           78            85.6                                          827    6           65            85.6                                          828    8           76            85.6                                          829    7           71            85.4                                          830    0           21            85.6                                          831    1           30            85.6                                          832    1           24            85.6                                          833    1           26            85.5                                          834    0           17            85.6                                          835    0           15            85.6                                          836    0           18            85.6                                          837    0           21            85.6                                          838    0           22            85.6                                          839    0           20            85.6                                          840    0           23            85.6                                          841    1           41            85.5                                          842    1           36            85.5                                          843    0           16            85.6                                          844    0           15            85.6                                          ______________________________________                                    

Example 9 (Experiment Nos. 901 to 923)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 1,000 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product (F), a water-soluble polymeric compound (D), a colloidal silica and/or an alkali metal silicate (E), a solvent and an alkaline compound given in Tables 35 and 36 under conditions given in Tables 35 and 36 (solvent composition, total concentration, (F):(D):(E) ratio and pH). The colloidal silicas used in this Example and Examples 10 to 12 below (a to g indicated in Tables 35, 36, 40-42, 46, 47 and 50-52) are shown in Table 39. The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 1. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 100 times. After the 100th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 1.

The results are given in Table 37 and 38.

                                      TABLE 35                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-Soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E):                                                                          Alkaline                    Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                    No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                        __________________________________________________________________________     901                                                                               44   --      --     Water:Methanol (90:10)                                                                     0.2      --     NaOH (9.5)                  902                                                                               54   --      --     Water:Methanol (90:10)                                                                     0.2      --     NaOH (9.5)                  903                                                                               60   --      --     Water:Methanol (90:10)                                                                     0.2      --     KOH (10.0)                  904                                                                               64   --      --     Water:Methanol (80:20)                                                                     0.3      --     KOH (10.0)                  905                                                                               56   --      --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (11.0)                 906                                                                               58   --      --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (11.0)                 907                                                                               20   Polyvinyl                                                                              a      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            NaOH (9.5)                          pyrrolidone                                                            908                                                                               23   Gelatin c      Water:Methanol (90:10)                                                                     0.3      100:100:100                                                                           NaOH (9.5)                  909                                                                               28   Polyvinyl                                                                              b      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            KOH (9.5)                           alcohol                                                                910                                                                               31   Pectin  a      Water:Methanol (90:10)                                                                     0.3      100:200:100                                                                           KOH (9.5)                   911                                                                               32   Polyacrylate                                                                           b      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                           KOH (10.5)                  912                                                                               33   Polyvinyl                                                                              c      Water:Methanol (90:10)                                                                     0.3      100:30:100                                                                            KOH (10.5)                          pyrrolidone                                                            __________________________________________________________________________

                                      TABLE 36                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-Soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E):                                                                          Alkaline                    Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                    No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                        __________________________________________________________________________     913                                                                               46   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            KOH (9.5)                   914                                                                               47   Gelatin b      Water:Methanol (90:10)                                                                     0.3      100:50:200                                                                            NaOH (9.5)                  915                                                                               50   Gelatin b      Water:Methanol (90:10)                                                                     0.3      100:100:100                                                                           NaOH (9.5)                  916                                                                               52   Pectin  c      Water:Methanol (90:10)                                                                     0.3      100:100:300                                                                           NaOH (10.0)                 917                                                                               54   Casein  c      Water:Methanol (90:10)                                                                     0.3      100:50:300                                                                            NaOH (11.0)                 918                                                                               62   Polyvinyl                                                                              a      Water:Methanol (80:20)                                                                     0.3      100:100:100                                                                           KOH (11.0)                          pyrrolidone                                                            919                                                                               64   Polyvinyl                                                                              a      Water:Methanol (80:20)                                                                     0.3      100:50:200                                                                            KOH (12.0)                          alcohol                                                                920                                                                               57   Gelatin b      Water:Methanol (80:20)                                                                     0.3      100:20:100                                                                            KOH (12.0)                  921                                                                               58   Gelatin f      Water:Methanol (80:20)                                                                     0.3      100:20:50                                                                             KOH (11.0)                  922                                                                               59   Gelatin c      Water:Methanol (80:20)                                                                     0.3      100:50:200                                                                            KOH (11.0)                  923                                                                               41   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            KOH (9.5)                   __________________________________________________________________________

                  TABLE 37                                                         ______________________________________                                         Results after 100th polymerization batch                                       Scale amount (g/m.sup.2)                                                       Exp.  Liquid  Around interface of                                                                           Number of                                         No.   phase   gas-liquid phases                                                                             fish eyes                                                                              L value                                   ______________________________________                                         901   0       235            26      71.9                                      902   0       245            27      71.8                                      903   0       220            26      71.2                                      904   0       215            24      71.1                                      905   0       220            25      71.2                                      906   0       210            24      71.2                                      907   0        38             8      72.5                                      908   0        54            10      72.5                                      909   0        42             8      72.5                                      910   0        55            10      72.4                                      911   0        41             8      72.4                                      912   0        47             9      72.4                                      ______________________________________                                    

                  TABLE 38                                                         ______________________________________                                         Results after 100th polymerization batch                                       Scale amount (g/m.sup.2)                                                       Exp.  Liquid  Around interface of                                                                           Number of                                         No.   phase   gas-liquid phases                                                                             fish eyes                                                                              L value                                   ______________________________________                                         913   0       2              4       72.6                                      914   0       2              5       72.6                                      925   0       3              4       72.6                                      916   0       2              4       72.6                                      917   0       4              5       72.6                                      918   0       2              4       71.9                                      919   0       2              4       71.8                                      920   0       3              4       71.9                                      921   0       4              5       71.9                                      922   0       3              4       71.9                                      923   0       45             9       72.5                                      ______________________________________                                    

                  TABLE 39                                                         ______________________________________                                         Colloidal                                                                               Particle diameter of                                                  silica   colloid particles Remarks*.sup.1                                      ______________________________________                                         a        5-7 μm         Snowtex CXS-9*.sup.2                                b        7-9 μm         Snowtex S*.sup.2                                    c        10-20 μm       Snowtex O*.sup.2                                    d        10-20 μm       Methanol                                                                       silica sol                                          e        10-20 μm       Ethylene glycol                                                                silica sol                                          f        10-20 μm       Snowtex N*.sup.2                                    g        10-20 μm       Snowtex C*.sup.2                                    ______________________________________                                          *1 All the products are produced by Nissan Chemical Industries, Ltd.           *2 Tradenames                                                            

Example 10 (Experiment Nos. 1001 to 1040)

In each experiment, a polymer scale preventive agent was prepared using a condensation product (F), a water-soluble polymeric compound (D), a colloidal silica and/or an alkali metal silicate (E), a solvent and an alkaline compound given in Tables 40-42 under conditions given in Tables 40-42 (solvent composition, total concentration, (F):(D):(E) ratio and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 1. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 150 times. After the 150th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

The number of fish eyes which may appear when a polymer is formed into sheet was measured with respect to the polymers produced in the experiments in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 1.

The results are given in Table 43-45.

                                      TABLE 40                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-Soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E):                                                                          Alkaline                    Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                    No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                        __________________________________________________________________________     1001                                                                              83   --      --     Water:Methanol (90:10)                                                                     0.2      --     NaOH (9.0)                  1002                                                                              103  --      --     Water:Methanol (90:10)                                                                     0.2      --     NaOH (9.0)                  1003                                                                              96   --      --     Water:Methanol (80:20)                                                                     0.3      --     KOH (9.5)                   1004                                                                              66   --      --     Water:Methanol (80:20)                                                                     0.3      --     KOH (9.5)                   1005                                                                              67   --      --     Water:Methanol (70:30)                                                                     0.3      --     KOH (10.0)                  1006                                                                              72   --      --     Water:Methanol (70:30)                                                                     0.3      --     KOH (10.5)                  1007                                                                              73   --      --     Water:Methanol (70:30)                                                                     0.3      --     KOH (11.0)                  1008                                                                              83   Gelatin a      Water:Methanol (90;10)                                                                     0.3      100:50:200                                                                            NaOH (9.0)                  1009                                                                              103  Polyvinyl                                                                              a      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            NaOH (9.0)                          alcohol                                                                1010                                                                              96   Polyvinyl                                                                              c      Water:Methanol (80:20                                                                      0.3      100:100:300                                                                           KOH (9.5)                           pyrrolidone                                                            1011                                                                              70   Pectin  c      Water:Methanol (70:30)                                                                     0.3      100:100:100                                                                           KOH (9.5)                   1012                                                                              80   Carboxymethyl                                                                          b      Water:Methanol (70:30)                                                                     0.3      100:100:100                                                                           KOH (10.0)                          cellulose                                                              1013                                                                              81   Gelatin b      Water:Methanol (70:30)                                                                     0.3      100:200:100                                                                           KOH (10.5)                  1014                                                                              75   Polyacrylate                                                                           b      Water:Methanol (70:30)                                                                     0.3      100:50:300                                                                            KOH (11.0)                  __________________________________________________________________________

                                      TABLE 41                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-Soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E):                                                                          Alkaline                    Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                    No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                        __________________________________________________________________________     1015                                                                              45   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                           NaOH (10.0)                 1016                                                                              46   Hydroxyethyl                                                                           c      Water:Methanol (90:10)                                                                     0.3      100:200:500                                                                           NaOH (10.0)                         cellulose                                                              1017                                                                              47   Polyvinyl                                                                              b      Water:Methanol (80:20)                                                                     0.3      100:50:100                                                                            KOH (10.0)                          pyrrolidone                                                            1018                                                                              48   Casein  f      Water:Methanol (80:20)                                                                     0.3      100:100:200                                                                           Ethylenedi-                                                                    amine (10.0)                1019                                                                              49   Pectin  g      Water:Methanol (80:20)                                                                     0.3      100:100:200                                                                           NaOH (9.0)                  1020                                                                              50   Polyacrylate                                                                           d      Water:Methanol (90:10)                                                                     0.5      100:30:200                                                                            NaOH (9.5)                  1021                                                                              60   Polyvinyl                                                                              Sodium Water:Methanol (90:10)                                                                     0.5      100: 10:200                                                                           NaOH (11.0)                         alcohol orthosilicate                                                  1022                                                                              64   Carboxymethyl                                                                          Sodium Water:Methanol (90:10)                                                                     0.3      100:50:300                                                                            KOH (11.0)                          cellulose                                                                              metasilicate                                                   1023                                                                              65   Gelatin c      Water:Methanol (80:20)                                                                     0.3      100:100:100                                                                           KOH (12.0)                  1024                                                                              55   Gelatin e      Water:Methanol (80:20)                                                                     0.3      100:20:50                                                                             NaOH (12.0)                 1025                                                                              58   Gelatin c      Water:Methanol (80:20)                                                                     0.3      100:50:200                                                                            NaOH (12.5)                 1026                                                                              84   Polyvinyl                                                                              d      Water:Methanol (80:20)                                                                     0.3      100:50:200                                                                            NaOH (9.5)                          pyrrolidone                                                            1027                                                                              86   Polyethylene                                                                           b      Water:Methanol (80:20)                                                                     0.3      100:100:100                                                                           NaOH (9.5)                          imine                                                                  __________________________________________________________________________

                                      TABLE 42                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-Soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E):                                                                          Alkaline                    Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                    No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                        __________________________________________________________________________     1028                                                                              87   Polyacrylate                                                                           b      Water:Methanol (70:30)                                                                     0.3      100:100:300                                                                           KOH (9.5)                   1029                                                                              88   Casein  c      Water:Methanol (70:30)                                                                     0.3      100:50:100                                                                            Ethylenedi-                                                                    amine (9.5)                 1030                                                                              89   Gelatin c      Water:Methanol (90:10)                                                                     0.3      100:30:200                                                                            NaOH (9.5)                  1031                                                                              103  Gelatin a      Water:Methanol (90:10)                                                                     0.5      100:200:100                                                                           NaOH (10.5)                 1032                                                                              104  Gelatin b      Water:Methanol (90:10)                                                                     0.5      100:100:100                                                                           NaOH (10.0)                 1033                                                                              105  Polyvinyl                                                                              b      Water:Methanol (90:10)                                                                     0.5      100:40:100                                                                            Triethanol-                         alcohol                                    amine (11.0)                1034                                                                              96   Polyacrylate                                                                           b      Water:Methanol (70:30)                                                                     0.5      100:10:100                                                                            NaOH (11.0)                 1035                                                                              97   Polyvinyl                                                                              b      Water:Methanol (90:10)                                                                     0.5      100:50:100                                                                            NaOH (11.0)                         alcohol                                                                1036                                                                              66   Gelatin a      Water:Methanol (95:5)                                                                      0.5      100:50:300                                                                            NaOH (11.0)                 1037                                                                              67   Gelatin c      Water:Methanol (95:5)                                                                      0.5      100:100:200                                                                           NaOH (9.5)                  1038                                                                              80   Gelatin f      Water:Methanol (90:10)                                                                     0.5      100:100:200                                                                           NaOH (9.5)                  1039                                                                              93   Pcetin  g      Water:Methanol (90:10)                                                                     0.5      100:10:200                                                                            NaOH (9.5)                  1040                                                                              95   Hydroxyethyl                                                                           a      Water:Methanol (90:10)                                                                     0.5      100:100:100                                                                           NaOH (9.5)                          cellulose                                                              __________________________________________________________________________

                  TABLE 43                                                         ______________________________________                                         Results after 150th polymerization batch                                       Scale amount (g/m.sup.2)                                                       Exp.  Liquid  Around interface of                                                                           Number of                                         No.   phase   gas-liquid phases                                                                             fish eyes                                                                              L value                                   ______________________________________                                         1001  2       120            17      72.5                                      1002  4       124            18      72.5                                      1003  5       133            18      72.4                                      1004  4       128            17      72.4                                      1005  3       135            19      72.5                                      1006  5       142            19      72.4                                      1007  4       126            17      72.5                                      1008  0        12             6      72.6                                      1009  0        10             6      72.6                                      1010  0        18             7      72.6                                      0111  0        11             6      72.6                                      1012  0        14             7      72.6                                      1013  0        13             6      72.6                                      1014  0        16             7      72.6                                      ______________________________________                                    

                  TABLE 44                                                         ______________________________________                                         Results after 150th polymerization batch                                       Scale amount (g/m.sup.2)                                                       Exp.  Liquid  Around interface of                                                                           Number of                                         No.   phase   gas-liquid phases                                                                             fish eyes                                                                              L value                                   ______________________________________                                         1015  0       80             13      72.4                                      1016  0       84             14      72.3                                      1017  0       91             15      72.4                                      1018  0       97             16      72.4                                      1019  0       83             14      72.3                                      1020  0       80             13      72.3                                      1021  0       80             13      72.4                                      1022  0       85             14      72.4                                      1023  0       98             17      72.4                                      1024  0       92             15      72.4                                      1025  0       95             16      72.4                                      1026  0       10              6      72.6                                      1027  0       13              7      72.5                                      ______________________________________                                    

                  TABLE 45                                                         ______________________________________                                         Results after 150th polymerization batch                                       Scale amount (g/m.sup.2)                                                       Exp.  Liquid  Around interface of                                                                           Number of                                         No.   phase   gas-liquid phases                                                                             fish eyes                                                                              L value                                   ______________________________________                                         1028  0       10             6       72.6                                      1029  0       13             7       72.5                                      1030  0       11             6       72.5                                      1031  0       14             7       72.5                                      1032  0       14             7       72.5                                      1033  0        9             6       72.6                                      1034  0        8             5       72.6                                      1035  0       12             6       72.6                                      1036  0       15             7       72.5                                      1037  0       10             6       72.6                                      1038  0        9             6       72.6                                      1039  0       31             8       72.5                                      1040  0       35             9       72.6                                      ______________________________________                                    

Example 11 (Experiment Nos. 1101 to 1121)

In each experiment, polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

First, a polymer scale preventive agent was prepared using a condensation product (F), a water-soluble polymeric compound (D), a colloidal silica and/or an alkali metal silicate (E), a solvent and an alkaline compound given in Tables 46 and 47 under conditions given in Tables 46 and 47 (solvent composition, total concentration, (F):(D):(E) ratio and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 2. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 50 times. After the 50th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 2.

The results are given in Table 48 and 49.

                                      TABLE 46                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)         (E)                Total                                           Conden-                                                                             (D)    Colloidal          concent-                                        sation                                                                              Water-soluble                                                                         silica and/or      ratoin of                                                                               (F):(D):(E)                                                                           Alkaline                     Exp.                                                                              Product                                                                             polymeric                                                                             alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                     No.                                                                               No.  compound                                                                              silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                         __________________________________________________________________________     1101                                                                              45   --     --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (9.0)                   1102                                                                              50   --     --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (9.5)                   1103                                                                              53   --     --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (9.5)                   1104                                                                              64   --     --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (10.0)                  1105                                                                              56   --     --     Water:Methanol (90:10)                                                                     0.3      --     NaOH (10.0)                  1106                                                                              18   Gelatin                                                                               a      Water:Methanol (80:20)                                                                     0.3       100:100:200                                                                          NaOH (9.5)                   1107                                                                              19   Pectin b      Water:Methanol (95:5)                                                                      0.3      100:30:100                                                                            NaOH (9.5)                   1108                                                                              24   Polyvinyl                                                                             a      Water:Methanol (90:10)                                                                     0.3       100:200:100                                                                          KOH (10.0)                           pyrrolidone                                                            1109                                                                              25   Gelatin                                                                               c      Water:Methanol (80:20)                                                                     0.3      100:50:200                                                                            KOH (10.0)                   1110                                                                              29   Polyvinyl                                                                             c      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                            Ethylenedi-                          alcohol                                   amine (10.5)                 1111                                                                              32   Polyacrylate                                                                          a      Water:Methanol (90:10)                                                                     0.3      100:50:50                                                                             Ethylenedi-                                                                    amine                        __________________________________________________________________________                                                       (10.5)                  

                                      TABLE 47                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)         (E)                Total                                           Conden-                                                                             (D)    Colloidal          concent-                                        sation                                                                              Water-soluble                                                                         silica and/or      ratoin of                                                                               (F):(D):(E)                                                                           Alkaline                     Exp.                                                                              Product                                                                             polymeric                                                                             alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                               compound                     No.                                                                               No.  compound                                                                              silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio) (pH)                         __________________________________________________________________________     1112                                                                              45   Gelatin                                                                               a      Water:Methanol (90:10)                                                                     0.3      100:50:200                                                                            NaOH (10.0)                  1113                                                                              50   Polyvinyl                                                                             c      Water:Methanol (90:10)                                                                     0.5      100:50:100                                                                            NaOH (10.0)                          alcohol                                                                1114                                                                              53   Polyvinyl                                                                             c      Water:Methanol (80:20)                                                                     0.5       100:100:100                                                                          Ethylenedi-                          pyrrolidone                               amine (11.0)                 1115                                                                              64   Gelatin                                                                               b      Water:Methanol (80:20)                                                                     0.3      100:50:100                                                                            KOH (11.0)                   1116                                                                              56   Casein b      Water:Methanol (70:30)                                                                     0.3      100:20:50                                                                             KOH (9.5)                    1117                                                                              55   Pectin b      Water:Methanol (95:5)                                                                      0.3      100:50:100                                                                            NaOH (9.5)                   1118                                                                              57   Polyacrylate                                                                          b      Water:Methanol (95:5)                                                                      0.3      100:50:200                                                                            NaOH (9.5)                   1119                                                                              58   Gelatin                                                                               a      Water:Methanol (90:10)                                                                     0.3      100:30:300                                                                            NaOH (9.5)                   1120                                                                              39   Gelatin                                                                               a      Water:Methanol (90:10)                                                                     0.3      100:50:200                                                                            NaOH (10.0)                  1121                                                                              40   Gelatin                                                                               a      Water:Methanol (90:10)                                                                     0.3      100:50:200                                                                            NaOH (10.0)                  __________________________________________________________________________

                  TABLE 48                                                         ______________________________________                                         Results after 50th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid     Around interface of                                          No.    phase      gas-liquid phases                                                                            L value                                        ______________________________________                                         1101   26         270           83.5                                           1102   25         250           83.6                                           1103   20         195           83.6                                           1104   28         290           83.4                                           1105   21         215           83.2                                           1106   0          23            85.5                                           1107   0          26            85.4                                           1108   2          38            85.4                                           1109   1          35            85.5                                           1110   0          25            85.5                                           1111   0          28            85.4                                           ______________________________________                                    

                  TABLE 49                                                         ______________________________________                                         Results after 50th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid     Around interface of                                          No.    phase      gas-liquid phases                                                                            L value                                        ______________________________________                                         1112   0          5             85.6                                           1113   0          5             85.6                                           1114   0          6             85.6                                           1115   0          5             85.6                                           1116   0          7             85.2                                           1117   0          5             85.2                                           1118   0          6             85.1                                           1119   0          5             85.1                                           1120   0          23            85.4                                           1121   2          38            85.5                                           ______________________________________                                    

Example 12 (Experiment Nos. 1201 to 1242)

First, a polymer scale preventive agent was prepared using a condensation product (F), a water-soluble polymeric compound (D), a colloidal silica and/or an alkali metal silicate (E), a solvent and an alkaline compound given in Tables 50-52 under conditions given in Tables 50-52 (solvent composition, total concentration, (F):(D):(E) ratio and pH). The polymer scale preventive agent was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 40° C. for 15 minutes to form a coating, which was then washed with water.

In the polymerization vessel in which the coating was formed as above, polymerization was carried out in the same manner as in Example 2. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 80 times. After the 80th batch, the amount of polymer scale on an area located in the liquid phase during polymerization and on an area in the vicinity of the interface between the gas and liquid phases, was measured in the same manner as in Example 1.

Further, to evaluate initial coloration at the time a polymer is formed into sheet, luminosity index L was measured in the same manner as in Example 2.

The results are given in Table 53-55.

                                      TABLE 50                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-soluble                                                                          silica and/or      ratoin of                                                                              (F):(D):(E)                                                                           Alkaline                     Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) +                                                                            (weight                                                                               compound                     No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (E) (wt. %)                                                                            ratio) (pH)                         __________________________________________________________________________     1201                                                                              83   --      --     Water:Methanol (90:10)                                                                     0.3     --     NaOH (9.5)                   1202                                                                              106  --      --     Water:Methanol (90:10)                                                                     0.3     --     Ethylenedi-                                                                    amine (9.5)                  1203                                                                              107  --      --     Water:Methanol (80:20)                                                                     0.3     --     NaOH (9.5)                   1204                                                                              68   --      --     Water:Methanol (80:20)                                                                     0.3     --     NaOH (10.0)                  1205                                                                              76   --      --     Water:Methanol (80:20)                                                                     0.3     --     NaOH (10.0)                  1206                                                                              77   --      --     Water:Methanol (80:20)                                                                     0.3     --     NaOH (10.0)                  1207                                                                              83   Gelatin a      Water:Methanol (90:10)                                                                     0.3     100:50:100                                                                            NaOH (9.5)                   1208                                                                              85   Polyacrylate                                                                           c      Water:Methanol (90:10)                                                                     0.3     100:30:200                                                                            KOH (9.5)                    1209                                                                              90   Polyvinyl                                                                              c      Water:Methanol (80:20)                                                                     0.3     100:50:100                                                                            NaOH (10.0)                          alcohol                                                                1210                                                                              91   Casein  b      Water:Methanol (80:20)                                                                     0.3      100:100:300                                                                          NaOH (10.0)                  1211                                                                              106  Pectin  b      Water:Methanol (80:20)                                                                     0.3      100:100:100                                                                          NaOH (10.0)                  1212                                                                              107  Gelatin a      Water:Methanol (80:20)                                                                     0.3     100:100:50                                                                            NaOH (10.0)                  1213                                                                              50   Polyacrylate                                                                           Litium Water:Methanol (90:10)                                                                     0.3     100:50:200                                                                            NaOH (10.0)                                  trisilicate                                                    1214                                                                              51   Polyacrylamide                                                                         a      Water:Methanol (90:10)                                                                     0.3     100:50:200                                                                            NaOH (10.0)                  __________________________________________________________________________

                                      TABLE 51                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-soluble                                                                          silica and/or      ratoin of                                                                              (F):(D):(E)                                                                           Alkaline                     Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) +                                                                            (weight                                                                               compound                     No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (E) (wt. %)                                                                            ratio) (pH)                         __________________________________________________________________________     1215                                                                              52   Hydroxyethyl                                                                           d      Water:Methanol (90:10)                                                                     0.3     100:50:200                                                                            NaOH (10.0)                          cellulose                                                              1216                                                                              53   Pectin  Sodium Water:Methanol (90:10)                                                                     0.3     100:50:200                                                                            NaOH (10.0)                                  metasilicate                                                   1217                                                                              54   Polyvinyl                                                                              c      Water:Methanol (80:20)                                                                     0.3      100:100:300                                                                          KOH (10.5)                           alcohol                                                                1218                                                                              61   Gelatin b      Water:Methanol (80:20)                                                                     0.3      100:100:300                                                                          KOH (10.5)                   1219                                                                              62   Casein  e      Water:Methanol (80:20)                                                                     0.3      100:100:300                                                                          KOH (10.5)                   1220                                                                              55   Pectin  c      Water:Methanol (80:20)                                                                     0.3      100:100:300                                                                          KOH (10.5)                   1221                                                                              57   Carboxymethyl                                                                          c      Water:Methanol (80:20)                                                                     0.3     100:50:200                                                                            Ethylenedi-                          cellulose                                 amine (9.5)                  1222                                                                              58   Casein  c      Water:Methanol (80:20)                                                                     0.3     100:50:100                                                                            Triethanol-                                                                    amine (10.5)                 1223                                                                              59   Gelatin c      Water:Methanol (95:5)                                                                      0.5     100:30:150                                                                            NaOH (10.0)                  1224                                                                              58   Polyacrylate                                                                           b      Water:Methanol (95:5)                                                                      0.5     100:30:150                                                                            NaOH (10.0)                  1225                                                                              58   Polyvinyl                                                                              f      Water:Methanol (95:5)                                                                      0.5     100:30:150                                                                            NaOH (10.0)                          pyrrolidone                                                            1226                                                                              58   Gelatin o      Water:Methanol (95:5)                                                                      0.5     100:30:150                                                                            NaOH (10.0)                  1227                                                                              59   Gelatin b      Water:Methanol (95:5)                                                                      0.5     100:30:150                                                                            NaOH (10.0)                  1228                                                                              108  Gelatin a      Water:Methanol (90:10)                                                                     0.3     100:50:100                                                                            NaOH (10.5)                  __________________________________________________________________________

                                      TABLE 52                                     __________________________________________________________________________     Polymer scale preventive agent                                                    (F)          (E)                Total                                          Conden-                                                                             (D)     Colloidal          concent-                                       sation                                                                              Water-soluble                                                                          silica and/or      ratoin of                                                                               (F):(D):(E)                                                                          Alkaline                     Exp.                                                                              Product                                                                             polymeric                                                                              alkali metal                                                                          Solvent     (F) + (D) + (E)                                                                         (weight                                                                              compound                     No.                                                                               No.  compound                                                                               silicate                                                                              (weight ratio)                                                                             (wt. %)  ratio)                                                                               (pH)                         __________________________________________________________________________     1229                                                                              109  Pectin  c      Water:Methanol (90:10)                                                                     0.3      100:200:300                                                                          NaOH (10.5)                  1230                                                                              110  Polyacrylate                                                                           c      Water:Methanol (90:10)                                                                     0.5      100:100:400                                                                          NaOH (10.5)                  1231                                                                              111  Polyacrylamide                                                                         c      Water:Methanol (90:10)                                                                     0.5      100:20:100                                                                           NaOH (10.5)                  1232                                                                              98   Hydroxyethyl                                                                           a      Water:Methanol (90:10)                                                                     0.5      100:100:300                                                                          NaOH (10.5)                          cellulose                                                              1233                                                                              99   Polyacrylate                                                                           b      Water:Methanol (80:20)                                                                     0.3      100:100:50                                                                           KOH (10.0)                   1234                                                                              100  Polyvinyl                                                                              b      Water:Methanol (80:20)                                                                     0.3      100:50:100                                                                           Ethylenedi-                          pyrrolidone                               amine (9.5)                  1235                                                                              101  Polyvinyl                                                                              c      Water:Methanol (80:20)                                                                     0.3      100:50:100                                                                           KOH (10.5)                           alcohol                                                                1236                                                                              102  Polyvinyl                                                                              c      Water:Methanol (90:10)                                                                     0.3      100:50:100                                                                           NaOH (11.0)                          alcohol                                                                1237                                                                              67   Polyvinyl                                                                              d      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (11.0)                          alcohol                                                                1238                                                                              69   Gelatin e      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (11.0)                  1239                                                                              92   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (11.0)                  1240                                                                              94   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (10.0)                  1241                                                                              74   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (10.0)                  1242                                                                              82   Gelatin a      Water:Methanol (90:10)                                                                     0.3      100:100:200                                                                          NaOH (10.0)                  __________________________________________________________________________

                  TABLE 53                                                         ______________________________________                                         Results after 80th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid     Around interface of                                          No.    phase      gas-liquid phases                                                                            L value                                        ______________________________________                                         1201   4          62            85.3                                           1202   5          68            85.3                                           1203   5          64            85.3                                           1204   7          78            85.2                                           1205   6          69            85.3                                           1206   4          57            85.3                                           1207   0           7            85.6                                           1208   0           5            85.5                                           1209   0           6            85.6                                           1210   0           5            85.6                                           1211   0           8            85.5                                           1212   0           5            85.6                                           1213   7          103           85.4                                           1214   9          114           85.3                                           ______________________________________                                    

                  TABLE 54                                                         ______________________________________                                         Results after 80th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid     Around interface of                                          No.    phase      gas-liquid phases                                                                            L value                                        ______________________________________                                         1215   8          110           85.3                                           1216   10         125           85.2                                           1217   6           98           85.4                                           1218   8          109           85.3                                           1219   5           91           85.3                                           1220   10         120           85.3                                           1221   5           95           85.4                                           1222   8          107           85.3                                           1223   6          102           85.4                                           1224   10         124           85.2                                           1225   8          112           85.3                                           1226   6           97           85.3                                           1227   9          121           85.3                                           1228   0           5            85.5                                           ______________________________________                                    

                  TABLE 55                                                         ______________________________________                                         Results after 80th polymerization batch                                        Scale amount (g/m.sup.2)                                                       Exp.   Liquid     Around interface of                                          No.    phase      gas-liquid phases                                                                            L value                                        ______________________________________                                         1229   0          6             85.6                                           1230   0          6             85.5                                           1231   0          6             85.5                                           1232   0          5             85.5                                           1233   0          5             85.6                                           1234   0          7             85.5                                           1235   0          5             85.6                                           1236   0          6             85.5                                           1237   0          5             85.6                                           1238   0          5             85.6                                           1239   0          45            85.2                                           1240   1          48            85.1                                           1241   0          5             85.6                                           1242   0          5             85.6                                           ______________________________________                                    

Example 13

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 1,000 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1213 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 10 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 400 kg of water, 260 kg of styrene, 140 kg of acrylonitrile, 400 g of a partially saponified product of a polyacrylamide and 1.2 kg of α,α'-azobisisobutyronitrile were charged, and polymerization was carried out at 90° C. for 5 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 50 times. After the 50th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 12 g/m².

Example 14

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1207 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 10 minutes to form a coating, which was then washed with water.

Thereafter, into the polymerization vessel in which the coating was formed as above, 9.5 kg of water, 240 g of sodium dodecylbenzenesulfonate, 15 g of t-dodecyl mercaptan, 2.1 kg of butadiene, 2.8 g of methyl methacrylate, 320 g of styrene and 16 g of potassium persulfate were charged. Polymerization was then carried out at 60° C. for 10 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 80 times. After the 80th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 9 g/m².

Example 15

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 100 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1233 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 15 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 40 kg of water, 500 g of a disproportionated potassium rhodinate, 13 kg of a polybutadiene latex (solid content: 45%), 9 kg of styrene monomer, 5 kg of acrylonitrile monomer, 40 g of t-dodecyl mercaptan, and 140 g of cumene hydroperoxide were charged. Thereafter, when the internal temperature became 47° C., 200 g of dextrose, 2 g of ferrous sulfate and 100 g of sodium pyrophosphate were charged in the vessel, followed by polymerization under stirring at 65° C. for 4 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 80 times. After the 80th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 8 g/m².

Example 16

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1218 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 15 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 4.0 kg of water and 6 g of sodium dodecylbenzenesulfonate were added, and they were heated to 60° C. under stirring. The air inside the polymerization vessel was replaced with a nitrogen gas, and thereafter 94 g of n-butyl acrylate, 220 g of methyl methacrylate, 5 g of acrylic acid and 5 g of methacrylic acid were added thereto. Subsequently, after 1 g of ammonium persulfate and 1 g of sodium hydrosulfite were added, stirring was continued at 60° C. for 20 minutes. Subsequently, a monomeric mixture containing 2.1 kg of n-butyl acrylate, 4.8 kg of methyl methacrylate, 100 g of acrylic acid and 100 g of methacrylic acid, 500 g of 1% by weight aqueous ammonium persulfate solution, 500 g of 1% by weight aqueous sodium hydrosulfite solution and 2.0 kg of 25% by weight polyoxyethylene nonylphenyl ether solution were added uniformly to the reaction mixture over 3 hours. After the addition, the reaction mixture was heated to 70° C. and polymerization was carried out for 2 hours. After the completion of the polymerization, the produced polymer was taken out and the unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 50 times. After the 50th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 13 g/m².

Example 17

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1236 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 60° C. for 10 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 4.5 kg of water, 312 g of a completely saponified polyvinyl alcohol, and 6 g of sodium carbonate were charged. Subsequently, the mixture was heated to 65° C. under stirring. After 550 g of vinyl acetate and 550 g of 1% by weight aqueous ammonium persulfate solution were added thereto, the mixture was heated to 80° C. Subsequently, 5.0 kg of vinyl acetate and 1.0 kg of 1% by weight aqueous ammonium persulfate solution were added thereto uniformly over 4 hours. After the addition of the vinyl acetate and ammonium persulfate, the reaction mixture was heated to 90° C. and polymerization was carried out at 90° C. for 2 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 80 times. After the 80th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 5 g/m².

Example 18

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1209 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 50° C. for 20 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 7.0 kg of water, 430 g of a partially saponified polyvinyl alcohol, 7 g of sodium pyrophosphate and 7 g of sodium hydrosulfite were added, and they were heated to 50° C. After the air inside the polymerization vessel was replaced with a nitrogen gas, the reaction mixture was heated to 70° C. Thereafter, ethylene was charged into the vessel until the internal pressure became 14 kg/cm².G. Subsequently, 6.0 kg of vinyl acetate and 1.0 kg of 2% by weight aqueous ammonium persulfate solution were added uniformly over 4 hours. After the addition of the vinyl acetate and ammonium persulfate, the reaction mixture was heated to 80° C., at which polymerization was carried out for 3 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 80 times. After the 80th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 7 g/m².

Example 19

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1021 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 60° C. for 20 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, an aqueous solution containing 1.2 kg of a polyvinyl alcohol with a saponification degree of 99.4 mole % and a polymerization degree of 2,250 in 15 liters of water was charged. To the aqueous solution under stirring, 1 kg of 35% concentrated hydrochloric acid was added. Ten minutes after the addition of the concentrated hydrochloric acid, 800 g of butyraldehyde was added dropwise thereto over 15 minutes. Thereafter, the reaction mixture was heated to 60° C., at which reaction was carried out for 3 hours. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 100 times. After the 100th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 8 g/m².

Example 20

1) Preparation of prepolymer

A prepolymer for use in this example was prepared as below.

A polymerization vessel was charged with 6,000 g of styrene monomer, 720 g of a polybutadiene rubber, 480 g of a mineral oil (tradename: CP-50, product of Idemitsu Kosan K.K.) and 6,000 g of n-dodecyl mercaptan, and they were allowed to react at 115° C. for 5 hours to produce a prepolymer.

2) Polymerization

Polymerization was conducted using a stainless steel polymerization vessel with an inner capacity of 20 liters and having a stirrer, as described below.

The polymer scale preventive agent used in Experiment No. 1020 was applied to the inner wall, the stirring shaft, the stirring blades and other areas with which a monomer comes into contact of the polymerization vessel. The applied polymer scale preventive agent was dried by heating at 60° C. for 10 minutes to form a coating, which was then washed with water.

Thereafter, in the polymerization vessel in which the coating was formed as above, 7,000 g of water, 7,000 g of the prepolymer prepared above, 70 g of hydroxyapatite, 0.14 g of sodium dodecylbenzenesulfonate, 17.5 g of benzoyl peroxide and 10.5 g of t-butyl perbenzoate were charged. Subsequently, reaction was carried out at 92° C. for 3.5 hours and then at 135° C. for 1 hour, to produce a polymer. After the completion of the polymerization, the produced polymer was taken out and unreacted monomer was recovered out of the polymerization vessel. Subsequently, the inside of the polymerization vessel was washed with water and residual resin was removed.

The batch above comprising the operations from forming a coating through polymerizing to washing with water was repeated 100 times. After the 100th batch, amount of polymer scale was measured in the same manner as in Example 1. Specifically, the amount of polymer scale on an area located in the liquid during polymerization was measured to be 0 g/m², and the amount of polymer scale on an area in the vicinity of the interface between the gas and liquid phases was measured to be 22 g/m². 

We claim:
 1. A process of producing a polymer of an ethylenically unsaturated double bond, which comprises polymerizing the monomer in a polymerization vessel having a polymer scale preventive coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution containing a condensation product of (A) an aromatic amine compound and (B) a quinone compound, followed by drying.
 2. The process of claim 1, wherein said polymerization is conducted as suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization or gas phase polymerization.
 3. The process of claim 1, wherein said monomer is selected from the group consisting of vinyl esters; vinyl halides; vinylidene halides; acrylic acid, methacrylic acid and their esters and salts; diene monomers; styrene; acrylonitrile; α-methylstyrene; and vinyl ethers.
 4. The process of claim 1, wherein the component (A) comprises at least one compound selected from the group consisting of (A-1) aromatic amine compounds having at least one group selected from the group consisting of hydroxyl group, carboxyl group and sulfo group, represented by the formulas (1), (2) and (3): ##STR13## wherein m is an integer of 1 to 5, R¹ stands for at least one group selected from the group consisting of --OH, --COOH and --SO₃ H and, where there exist two or more R¹ 's, the R¹ 's may be the same or different, and R² stands for at least one group selected from the group consisting of --H, --NH₂, --Cl, --NO₂, --COCH₃, --OCH₃, --N(CH₃)₂ and alkyl groups having 1 to 3 carbon atoms and, where there exist two or more R² 's, the R² 's may be the same or different; ##STR14## wherein m is as defined above, R¹ is as defined above and, where two or more R¹ 's are present, they may be the same or different, R² is as defined above and, where two or more R² 's are present, they may be the same or different, and n is an integer of 0 to 5; and ##STR15## wherein p is an integer of 0 to 4, q is an integer of 0 to 3, provided that p and q are not 0 at the same time, R² is as defined above and, where two or more R² 's are present, they may be the same or different, and R³ is at least one group selected from the group consisting of --OH, --COOH, CH₂ COOH, --CH₂ CH₂ COOH and --SO₃ H and, where two or more R³ 's are present, they may be the same or different; and (A-2) aromatic amine compounds free of hydroxyl group, carboxyl group and sulfo group represented by the formulas (4), (5) and (6): ##STR16## wherein R² may be the same and different and are each as defined above; ##STR17## wherein R² may be the same or different and are each as defined above; and ##STR18## wherein R² may be the same or different and are each as defined above.
 5. The process of claim 1, wherein the component (A) is an aromatic amine compound having at least one group selected from the group consisting of hydroxyl group, carboxyl group and sulfo group.
 6. The process of claim 1, wherein the component (A) comprises at least one aromatic amine compound having at least one group selected from the group consisting of hydroxyl group, carboxyl group and sulfo group and at least one aromatic amine compound free of hydroxyl group, carboxyl group and sulfo group.
 7. The process of claim 1, wherein the component (B) comprises at least one quinone compound selected from the group consisting of the compounds represented by the formulas (7), (8), (9) and (10): ##STR19## wherein R⁴ stands for --H , --NH₂, --Cl, --Br, --OH, --NO₂, --COCH₃, --OCH₃, --N(CH₃)₂ or an alkyl group having 1 to 3 carbon atoms, and R⁵ stands for --H, --NH₂, --CH₃, --OH, --COOH or --SO₃ H; ##STR20## wherein R⁴ and R⁵ are as defined above; ##STR21## wherein R⁴ and R⁵ are as defined above, and R⁶ stands for --H, --OH, --CH₃ --Cl, --Br, --COCH₃ --OCH₃ --COOH or --SO₃ H; and ##STR22## wherein R⁴, R⁵ and R⁶ are as defined above.
 8. The process of claim 1, wherein the condensation product has been produced by a process in which a condensation reaction of the components (A) and (B) is first initiated and thereafter a reaction stopper (C) is added to the reaction mixture for the condensation reaction.
 9. The process of claim 8, wherein the reaction stopper (C) is an inorganic reducing agent.
 10. The process of claim 8, wherein the reaction stopper (C) is an aromatic hydroxyl compound.
 11. The process of claim 8, wherein the reaction stopper (C) is an aromatic hydroxyl compound-based condensate.
 12. The process of claim 8, wherein the reaction stopper (C) is added to the reaction mixture at a time when reaction of the components (A) and (B) has reached a condensation conversion value in the range of 50 to 99% by weight.
 13. The process of claim 1, wherein the condensation product of the components (A) and (B) is contained in a concentration of about 0.001 to about 5% by weight of said alkaline solution.
 14. The process of claim 1, wherein said alkaline solution contains (E) at least one compound selected from the group consisting of colloidal silicas and alkali metal silicates. 